1283 lines
42 KiB
Rust
1283 lines
42 KiB
Rust
//! # Parsing
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//! This module is where the recursive-descent parsing methods live.
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//!
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//!
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//! # Schala EBNF Grammar
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//! This document is the authoritative grammar of Schala, represented in something approximating
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//! Extended Backus-Naur form. Terminal productions are in "double quotes", or UPPERCASE
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//! if they represent a class of tokens rather than an specific string, or are otherwise
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//! unreprsentable in ASCII.
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//!
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//! ## Top level structure
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//!
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//! ```text
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//! program := (statement delimiter)* EOF
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//! delimiter := NEWLINE | ";"
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//! statement := expression | declaration | import
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//! block := "{" (statement delimiter)* "}"
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//! declaration := type_declaration | func_declaration | binding_declaration | impl_declaration
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//! ```
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//! ## Declarations
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//!
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//! ### Types
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//! ```text
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//! type_declaration := "type" type_declaration_body
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//! type_declaration_body := "alias" type_alias | "mut"? type_singleton_name "=" type_body
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//! type_alias := IDENTIFIER "=" type_name
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//! type_body := variant_specifier ("|" variant_specifier)*
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//! variant_specifier := IDENTIFIER | IDENTIFIER "{" typed_identifier_list "}" | IDENTIFIER "(" type_name* ")"
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//! typed_identifier_list := typed_identifier*
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//! typed_identifier := IDENTIFIER type_anno
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//! ```
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//! ### Functions
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//!
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//! ```text
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//! func_declaration := func_signature func_body
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//! func_body := ε | nonempty_func_body
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//! nonempty_func_body := "{" (statement delimiter)* "}"
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//! func_signature := "fn" func_name formal_param_list type_anno+
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//! func_name := IDENTIFIER | operator
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//! formal_param_list := "(" (formal_param ",")* ")"
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//! formal_param := IDENTIFIER type_anno+
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//! ```
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//!
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//! ### Variable bindings
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//! ```text binding_declaration := "let" "mut"? IDENTIFIER "=" expresion```
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//!
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//! ### Interfaces
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//!
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//! ```text
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//! interface_declaration := "interface" type_singleton_name signature_block
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//! impl_declaration := "impl" type_singleton_name decl_block | "impl" type_singleton_name "for" type_name decl_block
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//! decl_block := "{" (func_declaration)* "}"
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//! signature_block := "{" (func_signature)* "}"
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//! ```
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//!
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//! ### Type Annotations
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//!
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//! ```text
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//! type_anno := ":" type_name
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//! type_name := type_singleton_name | "(" type_names ")"
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//! type_names := ε | type_name (, type_name)*
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//! type_singleton_name = IDENTIFIER (type_params)*
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//! type_params := "<" type_name (, type_name)* ">"
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//! ```
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//!
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//! ## Expressions
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//! ```text
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//! expression := precedence_expr type_anno+
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//! precedence_expr := prefix_expr
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//! prefix_expr := prefix_op call_expr
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//! prefix_op := "+" | "-" | "!" | "~"
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//! call_expr := index_expr ( "(" invocation_list ")" )* | ε
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//! invocation_list := invocation_argument ("," invocation_argument)* | ε
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//! invocation_argument := expression | IDENTIFIER "=" expression | "_"
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//! index_expr := primary ( "[" (expression ("," (expression)* | ε) "]" )*
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//! primary := literal | paren_expr | if_expr | for_expr | while_expr | identifier_expr | lambda_expr | anonymous_struct | list_expr
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//! expr_or_block := "{" (statement delimiter)* "}" | expr
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//! ```
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//!
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//! ### Primary expressions
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//!
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//! ```text
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//! list_expr := "[" (expression, ",")* "]"
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//! lambda_expr := "\\" lambda_param_list type_anno+ nonempty_func_body
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//! lambda_param_list := formal_param_list | formal_param
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//! paren_expr := "(" paren_inner ")"
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//! paren_inner := (expression ",")*
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//! identifier_expr := qualified_identifier | named_struct
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//! qualified_identifier := IDENTIFIER ("::" IDENTIFIER)*
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//! ```
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//!
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//! ## Literals
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//! ```text
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//! literal := "true" | "false" | number_literal | STR_LITERAL
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//! named_struct := qualified_identifier record_block
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//! record_block := "{" (record_entry, ",")* | "}" //TODO support anonymus structs, update syntax
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//! record_entry := IDENTIFIER ":" expression
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//! anonymous_struct := TODO
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//! number_literal := int_literal | float_literal
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//! int_literal = ("0x" | "0b") digits
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//! float_literal := digits ("." digits)
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//! digits := (digit_group underscore*)+
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//! digit_group := DIGIT+
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//! ```
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//!
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//! ### Patterns
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//! ```text
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//! pattern := "(" (pattern, ",")* ")" | simple_pattern
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//! simple_pattern := pattern_literal | record_pattern | tuple_struct_pattern
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//! pattern_literal := "true" | "false" | signed_number_literal | STR_LITERAL | qualified_identifier
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//! signed_number_literal := "-"? number_literal
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//! record_pattern := qualified_identifier "{" (record_pattern_entry, ",")* "}"
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//! record_pattern_entry := IDENTIFIER | IDENTIFIER ":" Pattern
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//! tuple_struct_pattern := qualified_identifier "(" (pattern, ",")* ")"
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//! ```
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//! ### If expressions
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//!
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//! TODO: it would be nice if the grammar could capture an incomplete precedence expr in the
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//! discriminator
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//!
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//! ```text
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//! if_expr := "if" discriminator if_expr_body
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//! if_expr_body := ("then" simple_conditional | "is" simple_pattern_match | cond_block)
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//! discriminator := ε | expression
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//! simple_conditional := expr_or_block else_case
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//! simple_pattern_match := pattern "then" simple_conditional
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//! else_case := "else" expr_or_block
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//!
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//! cond_block := "{" (cond_arm comma_or_delimiter)* "}"
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//! cond_arm := condition guard "then" expr_or_block | "else" expr_or_block
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//! condition := "is" pattern | operator precedence_expr | expression
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//! guard := "if" expression
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//! comma_or_delimiter := "," | delimiter
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//! ```
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//!
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//!
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//! ### While expressions
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//! ```text
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//! while_expr := "while" while_cond "{" (statement delimiter)* "}"
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//! while_cond := ε | expression | expression "is" pattern //TODO maybe is-expresions should be primary
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//! ```
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//!
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//! //TODO this implies there must be at least one enumerator, which the parser doesn"t support right
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//! //this second, and maybe should fail later anyway
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//! ### For-expressions
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//! ```text
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//! for_expr := "for" (enumerator | "{" enumerators "}") for_expr_body
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//! for_expr_body := "return" expression | "{" (statement delimiter)* "}"
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//! enumerators := enumerator ("," enumerators)*
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//! enumerator := identifier "<-" expression | identifier "=" expression //TODO add guards, etc.
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//! ```
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//! ## Imports
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//! ```text
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//! import := 'import' IDENTIFIER (:: IDENTIFIER)* import_suffix
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//! import_suffix := ε | '::{' IDENTIFIER (, IDENTIFIER)* '}' | '*' //TODO add qualified, exclusions, etc.
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//! ```
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mod test;
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use std::rc::Rc;
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use std::str::FromStr;
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use crate::tokenizing::*;
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use crate::tokenizing::Kw::*;
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use crate::tokenizing::TokenKind::*;
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use crate::ast::*;
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/// Represents a parsing error
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#[derive(Debug)]
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pub struct ParseError {
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pub production_name: Option<String>,
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pub msg: String,
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pub token: Token
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}
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impl ParseError {
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fn new_with_token<T, M>(msg: M, token: Token) -> ParseResult<T> where M: Into<String> {
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Err(ParseError { msg: msg.into(), token, production_name: None })
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}
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}
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/// Represents either a successful parsing result or a ParseError
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pub type ParseResult<T> = Result<T, ParseError>;
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#[derive(Debug)]
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pub struct ParseRecord {
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production_name: String,
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next_token: String,
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level: u32,
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}
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/// Main data structure for doing parsing.
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pub struct Parser {
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token_handler: TokenHandler,
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parse_record: Vec<ParseRecord>,
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parse_level: u32,
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restrictions: ParserRestrictions,
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id_store: ItemIdStore,
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}
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struct ParserRestrictions {
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no_struct_literal: bool
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}
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struct TokenHandler {
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tokens: Vec<Token>,
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idx: usize,
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end_of_file: (usize, usize),
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}
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impl TokenHandler {
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fn new(tokens: Vec<Token>) -> TokenHandler {
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let end_of_file = match tokens.last() {
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None => (0, 0),
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Some(t) => (t.line_num, t.char_num)
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};
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TokenHandler { idx: 0, tokens, end_of_file }
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}
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fn peek_kind(&mut self) -> TokenKind {
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self.peek().kind
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}
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fn peek_kind_n(&mut self, n: usize) -> TokenKind {
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self.peek_n(n).kind
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}
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fn peek(&mut self) -> Token {
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self.tokens.get(self.idx).map(|t: &Token| { t.clone()}).unwrap_or(Token { kind: TokenKind::EOF, line_num: self.end_of_file.0, char_num: self.end_of_file.1})
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}
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/// calling peek_n(0) is the same thing as peek()
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fn peek_n(&mut self, n: usize) -> Token {
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self.tokens.get(self.idx + n).map(|t: &Token| { t.clone()}).unwrap_or(Token { kind: TokenKind::EOF, line_num: self.end_of_file.0, char_num: self.end_of_file.1})
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}
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fn next(&mut self) -> Token {
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self.idx += 1;
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self.tokens.get(self.idx - 1).map(|t: &Token| { t.clone() }).unwrap_or(Token { kind: TokenKind::EOF, line_num: self.end_of_file.0, char_num: self.end_of_file.1})
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}
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}
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impl Parser {
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/// Create a new parser initialized with some tokens.
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pub fn new(initial_input: Vec<Token>) -> Parser {
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Parser {
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token_handler: TokenHandler::new(initial_input),
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parse_record: vec![],
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parse_level: 0,
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restrictions: ParserRestrictions { no_struct_literal: false },
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id_store: ItemIdStore::new(),
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}
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}
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/// Parse all loaded tokens up to this point.
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pub fn parse(&mut self) -> ParseResult<AST> {
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self.program()
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}
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/*
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pub fn parse_with_new_tokens(&mut self, new_tokens: Vec<Token>) -> ParseResult<AST> {
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}
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*/
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pub fn format_parse_trace(&self) -> String {
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let mut buf = String::new();
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buf.push_str("Parse productions:\n");
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for r in self.parse_record.iter() {
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let mut indent = String::new();
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for _ in 0..r.level {
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indent.push('.');
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}
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buf.push_str(&format!("{}`{}`, next token: {}\n", indent, r.production_name, r.next_token))
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}
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buf
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}
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}
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macro_rules! print_token_pattern {
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($tokenpattern:pat) => { stringify!($tokenpattern) }
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}
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macro_rules! expect {
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($self:expr, $token_kind:pat) => { expect!($self, $token_kind if true) };
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($self:expr, $expected_kind:pat if $cond:expr) => {
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{
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let tok = $self.token_handler.peek();
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match tok.get_kind() {
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$expected_kind if $cond => $self.token_handler.next(),
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actual_kind => {
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let msg = format!("Expected {}, got {:?}", print_token_pattern!($expected_kind), actual_kind);
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return ParseError::new_with_token(msg, tok);
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}
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}
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}
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}
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}
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macro_rules! delimited {
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($self:expr, $start:pat, $parse_fn:ident, $( $delim:pat )|+, $end:pat, nonstrict) => {
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delimited!($self, $start, $parse_fn, $( $delim )|*, $end, false)
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};
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($self:expr, $start:pat, $parse_fn:ident, $( $delim:pat )|+, $end:pat) => {
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delimited!($self, $start, $parse_fn, $( $delim )|*, $end, true)
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};
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($self:expr, $start:pat, $parse_fn:ident, $( $delim:pat )|+, $end:pat, $strictness:expr) => {
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{
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expect!($self, $start);
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let mut acc = vec![];
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loop {
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let peek = $self.token_handler.peek();
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match peek.get_kind() {
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$end | EOF => break,
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_ => (),
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}
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if !$strictness {
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match peek.get_kind() {
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$( $delim )|* => { $self.token_handler.next(); continue },
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_ => ()
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}
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}
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acc.push($self.$parse_fn()?);
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match $self.token_handler.peek().get_kind() {
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$( $delim )|* => { $self.token_handler.next(); continue },
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_ if $strictness => break,
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_ => continue,
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};
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}
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expect!($self, $end);
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acc
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}
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};
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}
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impl Parser {
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/// `program := (statement delimiter)* EOF`
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/// `delimiter := NEWLINE | ';'`
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#[recursive_descent_method]
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fn program(&mut self) -> ParseResult<AST> {
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let mut statements = Vec::new();
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loop {
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match self.token_handler.peek().get_kind() {
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EOF => break,
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Newline | Semicolon => {
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self.token_handler.next();
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continue;
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},
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_ => statements.push(
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self.statement()?
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),
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}
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}
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Ok(AST { id: self.id_store.fresh(), statements })
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}
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/// `statement := expression | declaration`
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#[recursive_descent_method]
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fn statement(&mut self) -> ParseResult<Statement> {
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//TODO handle error recovery here
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let kind = match self.token_handler.peek().get_kind() {
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Keyword(Type) => self.type_declaration().map(|decl| { StatementKind::Declaration(decl) }),
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Keyword(Func)=> self.func_declaration().map(|func| { StatementKind::Declaration(func) }),
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Keyword(Let) => self.binding_declaration().map(|decl| StatementKind::Declaration(decl)),
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Keyword(Interface) => self.interface_declaration().map(|decl| StatementKind::Declaration(decl)),
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Keyword(Impl) => self.impl_declaration().map(|decl| StatementKind::Declaration(decl)),
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Keyword(Import) => self.import_declaration().map(|spec| StatementKind::Import(spec)),
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_ => self.expression().map(|expr| { StatementKind::Expression(expr) } ),
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}?;
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Ok(Statement { kind, id: self.id_store.fresh() })
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}
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#[recursive_descent_method]
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fn type_declaration(&mut self) -> ParseResult<Declaration> {
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expect!(self, Keyword(Type));
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self.type_declaration_body()
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}
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#[recursive_descent_method]
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fn type_declaration_body(&mut self) -> ParseResult<Declaration> {
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if let Keyword(Alias) = self.token_handler.peek_kind() {
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self.type_alias()
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} else {
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let mutable = if let Keyword(Mut) = self.token_handler.peek_kind() {
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self.token_handler.next();
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true
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} else {
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false
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};
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let name = self.type_singleton_name()?;
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expect!(self, Equals);
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let body = self.type_body()?;
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Ok(Declaration::TypeDecl { name, body, mutable})
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}
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}
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#[recursive_descent_method]
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fn type_alias(&mut self) -> ParseResult<Declaration> {
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expect!(self, Keyword(Alias));
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let alias = self.identifier()?;
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expect!(self, Equals);
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let original = self.identifier()?;
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Ok(Declaration::TypeAlias { alias, original })
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}
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#[recursive_descent_method]
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fn type_body(&mut self) -> ParseResult<TypeBody> {
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let mut variants = Vec::new();
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variants.push(self.variant_specifier()?);
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loop {
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if let Pipe = self.token_handler.peek_kind() {
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self.token_handler.next();
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variants.push(self.variant_specifier()?);
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} else {
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break;
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}
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}
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Ok(TypeBody(variants))
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}
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#[recursive_descent_method]
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fn variant_specifier(&mut self) -> ParseResult<Variant> {
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use self::Variant::*;
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let name = self.identifier()?;
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match self.token_handler.peek_kind() {
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LParen => {
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let tuple_members = delimited!(self, LParen, type_name, Comma, RParen);
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Ok(TupleStruct(name, tuple_members))
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},
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LCurlyBrace => {
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let typed_identifier_list = delimited!(self, LCurlyBrace, typed_identifier, Comma, RCurlyBrace);
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Ok(Record {name, members: typed_identifier_list })
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},
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_ => Ok(UnitStruct(name))
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}
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}
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#[recursive_descent_method]
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fn typed_identifier(&mut self) -> ParseResult<(Rc<String>, TypeIdentifier)> {
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let identifier = self.identifier()?;
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expect!(self, Colon);
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let type_name = self.type_name()?;
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Ok((identifier, type_name))
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}
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#[recursive_descent_method]
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fn func_declaration(&mut self) -> ParseResult<Declaration> {
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let signature = self.func_signature()?;
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if let LCurlyBrace = self.token_handler.peek_kind() {
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let statements = self.nonempty_func_body()?;
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Ok(Declaration::FuncDecl(signature, statements))
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} else {
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Ok(Declaration::FuncSig(signature))
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}
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}
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#[recursive_descent_method]
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fn func_signature(&mut self) -> ParseResult<Signature> {
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expect!(self, Keyword(Func));
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let (name, operator) = match self.token_handler.peek_kind() {
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Operator(s) => {
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let name = s.clone();
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self.token_handler.next();
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(name, true)
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},
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_ => (self.identifier()?, false)
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};
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let params = self.formal_param_list()?;
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let type_anno = match self.token_handler.peek_kind() {
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Colon => Some(self.type_anno()?),
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_ => None,
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};
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Ok(Signature { name, operator, params, type_anno })
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}
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#[recursive_descent_method]
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fn nonempty_func_body(&mut self) -> ParseResult<Vec<Statement>> {
|
|
let statements = delimited!(self, LCurlyBrace, statement, Newline | Semicolon, RCurlyBrace, nonstrict);
|
|
Ok(statements)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn formal_param_list(&mut self) -> ParseResult<Vec<FormalParam>> {
|
|
Ok(delimited!(self, LParen, formal_param, Comma, RParen))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn formal_param(&mut self) -> ParseResult<FormalParam> {
|
|
let name = self.identifier()?;
|
|
let anno = match self.token_handler.peek_kind() {
|
|
Colon => Some(self.type_anno()?),
|
|
_ => None
|
|
};
|
|
let default = match self.token_handler.peek_kind() {
|
|
Equals => {
|
|
self.token_handler.next();
|
|
Some(self.expression()?)
|
|
},
|
|
_ => None
|
|
};
|
|
Ok(FormalParam { name, anno, default })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn binding_declaration(&mut self) -> ParseResult<Declaration> {
|
|
expect!(self, Keyword(Kw::Let));
|
|
let constant = match self.token_handler.peek_kind() {
|
|
Keyword(Kw::Mut) => {
|
|
self.token_handler.next();
|
|
false
|
|
}
|
|
_ => true
|
|
};
|
|
let name = self.identifier()?;
|
|
let type_anno = if let Colon = self.token_handler.peek_kind() {
|
|
Some(self.type_anno()?)
|
|
} else {
|
|
None
|
|
};
|
|
|
|
expect!(self, Equals);
|
|
let expr = self.expression()?;
|
|
|
|
Ok(Declaration::Binding { name, constant, type_anno, expr })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn interface_declaration(&mut self) -> ParseResult<Declaration> {
|
|
expect!(self, Keyword(Interface));
|
|
let name = self.identifier()?;
|
|
let signatures = self.signature_block()?;
|
|
Ok(Declaration::Interface { name, signatures })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn signature_block(&mut self) -> ParseResult<Vec<Signature>> {
|
|
Ok(delimited!(self, LCurlyBrace, func_signature, Newline | Semicolon, RCurlyBrace, nonstrict))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn impl_declaration(&mut self) -> ParseResult<Declaration> {
|
|
expect!(self, Keyword(Impl));
|
|
let first = self.type_singleton_name()?;
|
|
let second = if let Keyword(For) = self.token_handler.peek_kind() {
|
|
self.token_handler.next();
|
|
Some(self.type_name()?)
|
|
} else {
|
|
None
|
|
};
|
|
|
|
let block = self.decl_block()?;
|
|
Ok(match (first, second) {
|
|
(interface_name, Some(type_name)) =>
|
|
Declaration::Impl { type_name, interface_name: Some(interface_name), block },
|
|
(type_singleton_name, None) =>
|
|
Declaration::Impl { type_name: TypeIdentifier::Singleton(type_singleton_name), interface_name: None, block }
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn decl_block(&mut self) -> ParseResult<Vec<Declaration>> {
|
|
Ok(delimited!(self, LCurlyBrace, func_declaration, Newline | Semicolon, RCurlyBrace, nonstrict))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn expression(&mut self) -> ParseResult<Expression> {
|
|
let mut expr_body = self.precedence_expr(BinOp::min_precedence())?;
|
|
let type_anno = match self.token_handler.peek_kind() {
|
|
Colon => Some(self.type_anno()?),
|
|
_ => None
|
|
};
|
|
if let Some(_) = expr_body.type_anno {
|
|
return ParseError::new_with_token("Bad parse state encountered", self.token_handler.peek());
|
|
}
|
|
expr_body.type_anno = type_anno;
|
|
Ok(expr_body)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn type_anno(&mut self) -> ParseResult<TypeIdentifier> {
|
|
expect!(self, Colon);
|
|
self.type_name()
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn type_name(&mut self) -> ParseResult<TypeIdentifier> {
|
|
use self::TypeIdentifier::*;
|
|
Ok(match self.token_handler.peek_kind() {
|
|
LParen => Tuple(delimited!(self, LParen, type_name, Comma, RParen)),
|
|
_ => Singleton(self.type_singleton_name()?),
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn type_singleton_name(&mut self) -> ParseResult<TypeSingletonName> {
|
|
Ok(TypeSingletonName {
|
|
name: self.identifier()?,
|
|
params: match self.token_handler.peek_kind() {
|
|
LAngleBracket => delimited!(self, LAngleBracket, type_name, Comma, RAngleBracket),
|
|
_ => vec![],
|
|
}
|
|
})
|
|
}
|
|
|
|
// this implements Pratt parsing, see http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
|
|
fn precedence_expr(&mut self, precedence: i32) -> ParseResult<Expression> {
|
|
let record = ParseRecord {
|
|
production_name: "precedence_expr".to_string(),
|
|
next_token: format!("{}", self.token_handler.peek().to_string_with_metadata()),
|
|
level: self.parse_level,
|
|
};
|
|
self.parse_level += 1;
|
|
self.parse_record.push(record);
|
|
|
|
let mut lhs = self.prefix_expr()?;
|
|
loop {
|
|
let new_precedence = match BinOp::get_precedence_from_token(&self.token_handler.peek_kind()) {
|
|
Some(p) => p,
|
|
None => break,
|
|
};
|
|
|
|
if precedence >= new_precedence {
|
|
break;
|
|
}
|
|
let next_tok = self.token_handler.next();
|
|
let operation = match BinOp::from_sigil_token(&next_tok.kind) {
|
|
Some(sigil) => sigil,
|
|
//TODO I think I can fix this unreachable
|
|
None => unreachable!()
|
|
};
|
|
let rhs = self.precedence_expr(new_precedence)?;
|
|
lhs = Expression::new(self.id_store.fresh(), ExpressionKind::BinExp(operation, bx!(lhs), bx!(rhs)));
|
|
}
|
|
self.parse_level -= 1;
|
|
Ok(lhs)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn prefix_expr(&mut self) -> ParseResult<Expression> {
|
|
match self.token_handler.peek_kind() {
|
|
Operator(ref op) if PrefixOp::is_prefix(&*op) => {
|
|
let sigil = match self.token_handler.next().kind {
|
|
Operator(op) => op,
|
|
_ => unreachable!(),
|
|
};
|
|
let expr = self.primary()?;
|
|
let prefix_op = PrefixOp::from_str(sigil.as_str()).unwrap();
|
|
Ok(Expression::new(
|
|
self.id_store.fresh(),
|
|
ExpressionKind::PrefixExp(prefix_op, bx!(expr))
|
|
))
|
|
},
|
|
_ => self.call_expr()
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn call_expr(&mut self) -> ParseResult<Expression> {
|
|
let mut expr = self.index_expr()?;
|
|
while let LParen = self.token_handler.peek_kind() {
|
|
let arguments = delimited!(self, LParen, invocation_argument, Comma, RParen);
|
|
expr = Expression::new(self.id_store.fresh(), ExpressionKind::Call { f: bx!(expr), arguments }); //TODO no type anno is incorrect
|
|
}
|
|
|
|
Ok(expr)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn invocation_argument(&mut self) -> ParseResult<InvocationArgument> {
|
|
Ok(match self.token_handler.peek_kind() {
|
|
Underscore => {
|
|
self.token_handler.next();
|
|
InvocationArgument::Ignored
|
|
},
|
|
Identifier(s) => {
|
|
match self.token_handler.peek_kind_n(1) {
|
|
Equals => {
|
|
self.token_handler.next();
|
|
self.token_handler.next();
|
|
let expr = self.expression()?;
|
|
InvocationArgument::Keyword { name: s.clone(), expr }
|
|
},
|
|
_ => {
|
|
let expr = self.expression()?;
|
|
InvocationArgument::Positional(expr)
|
|
}
|
|
}
|
|
},
|
|
_ => InvocationArgument::Positional(self.expression()?)
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn index_expr(&mut self) -> ParseResult<Expression> {
|
|
let primary = self.primary()?;
|
|
Ok(if let LSquareBracket = self.token_handler.peek_kind() {
|
|
let indexers = delimited!(self, LSquareBracket, expression, Comma, RSquareBracket);
|
|
Expression::new(self.id_store.fresh(), ExpressionKind::Index {
|
|
indexee: bx!(Expression::new(self.id_store.fresh(), primary.kind)),
|
|
indexers,
|
|
})
|
|
} else {
|
|
primary
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn primary(&mut self) -> ParseResult<Expression> {
|
|
match self.token_handler.peek_kind() {
|
|
LCurlyBrace => self.curly_brace_expr(),
|
|
Backslash => self.lambda_expr(),
|
|
LParen => self.paren_expr(),
|
|
LSquareBracket => self.list_expr(),
|
|
Keyword(Kw::If) => self.if_expr(),
|
|
Keyword(Kw::For) => self.for_expr(),
|
|
Keyword(Kw::While) => self.while_expr(),
|
|
Identifier(_) => self.identifier_expr(),
|
|
_ => self.literal(),
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn list_expr(&mut self) -> ParseResult<Expression> {
|
|
let exprs = delimited!(self, LSquareBracket, expression, Comma, RSquareBracket);
|
|
Ok(Expression::new(self.id_store.fresh(), ExpressionKind::ListLiteral(exprs)))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn curly_brace_expr(&mut self) -> ParseResult<Expression> {
|
|
ParseError::new_with_token("Not implemented", self.token_handler.peek())
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn lambda_expr(&mut self) -> ParseResult<Expression> {
|
|
expect!(self, Backslash);
|
|
let params = self.lambda_param_list()?;
|
|
let type_anno = match self.token_handler.peek_kind() {
|
|
Colon => Some(self.type_anno()?),
|
|
_ => None,
|
|
};
|
|
let body = self.nonempty_func_body()?;
|
|
Ok(Expression::new(self.id_store.fresh(), ExpressionKind::Lambda { params, type_anno, body })) //TODO need to handle types somehow
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn lambda_param_list(&mut self) -> ParseResult<Vec<FormalParam>> {
|
|
if let LParen = self.token_handler.peek_kind() {
|
|
self.formal_param_list()
|
|
} else {
|
|
let single_param = self.formal_param()?;
|
|
Ok(vec![single_param])
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn paren_expr(&mut self) -> ParseResult<Expression> {
|
|
use self::ExpressionKind::*;
|
|
let old_struct_value = self.restrictions.no_struct_literal;
|
|
self.restrictions.no_struct_literal = false;
|
|
let output = {
|
|
let mut inner = delimited!(self, LParen, expression, Comma, RParen);
|
|
match inner.len() {
|
|
0 => Ok(Expression::new(self.id_store.fresh(), TupleLiteral(vec![]))),
|
|
1 => Ok(inner.pop().unwrap()),
|
|
_ => Ok(Expression::new(self.id_store.fresh(), TupleLiteral(inner)))
|
|
}
|
|
};
|
|
self.restrictions.no_struct_literal = old_struct_value;
|
|
output
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn identifier_expr(&mut self) -> ParseResult<Expression> {
|
|
use self::ExpressionKind::*;
|
|
let components = self.qualified_identifier()?;
|
|
let qualified_identifier = QualifiedName { id: self.id_store.fresh(), components };
|
|
Ok(match self.token_handler.peek_kind() {
|
|
LCurlyBrace if !self.restrictions.no_struct_literal => {
|
|
let fields = self.record_block()?;
|
|
Expression::new(self.id_store.fresh(), NamedStruct { name: qualified_identifier, fields })
|
|
},
|
|
_ => Expression::new(self.id_store.fresh(), Value(qualified_identifier))
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn qualified_identifier(&mut self) -> ParseResult<Vec<Rc<String>>> {
|
|
let mut components = vec![self.identifier()?];
|
|
loop {
|
|
match (self.token_handler.peek_kind(), self.token_handler.peek_kind_n(1)) {
|
|
(Colon, Colon) => {
|
|
self.token_handler.next(); self.token_handler.next();
|
|
components.push(self.identifier()?);
|
|
},
|
|
_ => break,
|
|
}
|
|
}
|
|
Ok(components)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn record_block(&mut self) -> ParseResult<Vec<(Rc<String>, Expression)>> {
|
|
Ok(delimited!(self, LCurlyBrace, record_entry, Comma, RCurlyBrace))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn record_entry(&mut self) -> ParseResult<(Rc<String>, Expression)> {
|
|
let field_name = self.identifier()?;
|
|
expect!(self, Colon);
|
|
let value = self.expression()?;
|
|
Ok((field_name, value))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn if_expr(&mut self) -> ParseResult<Expression> {
|
|
expect!(self, Keyword(Kw::If));
|
|
let old_struct_value = self.restrictions.no_struct_literal;
|
|
self.restrictions.no_struct_literal = true;
|
|
let discriminator = if let LCurlyBrace = self.token_handler.peek_kind() {
|
|
None
|
|
} else {
|
|
Some(Box::new(self.expression()?))
|
|
};
|
|
let body = Box::new(self.if_expr_body()?);
|
|
self.restrictions.no_struct_literal = old_struct_value;
|
|
Ok(Expression::new(self.id_store.fresh(), ExpressionKind::IfExpression { discriminator, body }))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn if_expr_body(&mut self) -> ParseResult<IfExpressionBody> {
|
|
match self.token_handler.peek_kind() {
|
|
Keyword(Kw::Then) => self.simple_conditional(),
|
|
Keyword(Kw::Is) => self.simple_pattern_match(),
|
|
_ => self.cond_block(),
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn simple_conditional(&mut self) -> ParseResult<IfExpressionBody> {
|
|
expect!(self, Keyword(Kw::Then));
|
|
let then_case = self.expr_or_block()?;
|
|
let else_case = self.else_case()?;
|
|
Ok(IfExpressionBody::SimpleConditional {then_case, else_case })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn simple_pattern_match(&mut self) -> ParseResult<IfExpressionBody> {
|
|
expect!(self, Keyword(Kw::Is));
|
|
let pattern = self.pattern()?;
|
|
expect!(self, Keyword(Kw::Then));
|
|
let then_case = self.expr_or_block()?;
|
|
let else_case = self.else_case()?;
|
|
Ok(IfExpressionBody::SimplePatternMatch { pattern, then_case, else_case })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn else_case(&mut self) -> ParseResult<Option<Block>> {
|
|
Ok(if let Keyword(Kw::Else) = self.token_handler.peek_kind() {
|
|
self.token_handler.next();
|
|
Some(self.expr_or_block()?)
|
|
} else {
|
|
None
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn cond_block(&mut self) -> ParseResult<IfExpressionBody> {
|
|
expect!(self, LCurlyBrace);
|
|
let mut cond_arms = vec![];
|
|
loop {
|
|
match self.token_handler.peek_kind() {
|
|
RCurlyBrace | EOF => break,
|
|
Semicolon | Newline => { self.token_handler.next(); continue},
|
|
_ => {
|
|
cond_arms.push(self.cond_arm()?);
|
|
match self.token_handler.peek_kind() {
|
|
Comma | Semicolon | Newline => { self.token_handler.next(); continue; },
|
|
_ => break,
|
|
}
|
|
}
|
|
}
|
|
}
|
|
expect!(self, RCurlyBrace);
|
|
Ok(IfExpressionBody::CondList(cond_arms))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn cond_arm(&mut self) -> ParseResult<ConditionArm> {
|
|
let (condition, guard) = if let Keyword(Kw::Else) = self.token_handler.peek_kind() {
|
|
self.token_handler.next();
|
|
(Condition::Else, None)
|
|
} else {
|
|
let condition = self.condition()?;
|
|
let guard = self.guard()?;
|
|
expect!(self, Keyword(Kw::Then));
|
|
(condition, guard)
|
|
};
|
|
let body = self.expr_or_block()?;
|
|
Ok(ConditionArm { condition, guard, body })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn condition(&mut self) -> ParseResult<Condition> {
|
|
Ok(match self.token_handler.peek_kind() {
|
|
Keyword(Kw::Is) => {
|
|
self.token_handler.next();
|
|
Condition::Pattern(self.pattern()?)
|
|
},
|
|
ref tok if BinOp::from_sigil_token(tok).is_some() => {
|
|
let op = BinOp::from_sigil_token(&self.token_handler.next().kind).unwrap();
|
|
let expr = self.expression()?;
|
|
Condition::TruncatedOp(op, expr)
|
|
},
|
|
_ => {
|
|
Condition::Expression(self.expression()?)
|
|
},
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn guard(&mut self) -> ParseResult<Option<Expression>> {
|
|
Ok(match self.token_handler.peek_kind() {
|
|
Keyword(Kw::If) => {
|
|
self.token_handler.next();
|
|
Some(self.expression()?)
|
|
},
|
|
_ => None
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn pattern(&mut self) -> ParseResult<Pattern> {
|
|
if let LParen = self.token_handler.peek_kind() {
|
|
let tuple_pattern_variants = delimited!(self, LParen, pattern, Comma, RParen);
|
|
Ok(Pattern::TuplePattern(tuple_pattern_variants))
|
|
} else {
|
|
self.simple_pattern()
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn simple_pattern(&mut self) -> ParseResult<Pattern> {
|
|
Ok(match self.token_handler.peek_kind() {
|
|
Identifier(_) => {
|
|
let components = self.qualified_identifier()?;
|
|
let qualified_identifier = QualifiedName { id: self.id_store.fresh(), components };
|
|
match self.token_handler.peek_kind() {
|
|
LCurlyBrace => {
|
|
let members = delimited!(self, LCurlyBrace, record_pattern_entry, Comma, RCurlyBrace);
|
|
Pattern::Record(qualified_identifier, members)
|
|
},
|
|
LParen => {
|
|
let members = delimited!(self, LParen, pattern, Comma, RParen);
|
|
Pattern::TupleStruct(qualified_identifier, members)
|
|
},
|
|
_ => {
|
|
Pattern::VarOrName(qualified_identifier)
|
|
},
|
|
}
|
|
},
|
|
_ => self.pattern_literal()?
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn pattern_literal(&mut self) -> ParseResult<Pattern> {
|
|
let tok = self.token_handler.peek();
|
|
Ok(match tok.get_kind() {
|
|
Keyword(Kw::True) => {
|
|
self.token_handler.next();
|
|
Pattern::Literal(PatternLiteral::BoolPattern(true))
|
|
},
|
|
Keyword(Kw::False) => {
|
|
self.token_handler.next();
|
|
Pattern::Literal(PatternLiteral::BoolPattern(false))
|
|
},
|
|
StrLiteral(s) => {
|
|
self.token_handler.next();
|
|
Pattern::Literal(PatternLiteral::StringPattern(s))
|
|
},
|
|
DigitGroup(_) | HexLiteral(_) | BinNumberSigil | Period => self.signed_number_literal()?,
|
|
Operator(ref op) if **op == "-" => self.signed_number_literal()?,
|
|
Underscore => {
|
|
self.token_handler.next();
|
|
Pattern::Ignored
|
|
},
|
|
other => return ParseError::new_with_token(format!("{:?} is not a valid Pattern", other), tok)
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn signed_number_literal(&mut self) -> ParseResult<Pattern> {
|
|
let neg = match self.token_handler.peek_kind() {
|
|
Operator(ref op) if **op == "-" => {
|
|
self.token_handler.next();
|
|
true
|
|
},
|
|
_ => false
|
|
};
|
|
let Expression { kind, .. } = self.number_literal()?;
|
|
Ok(Pattern::Literal(PatternLiteral::NumPattern { neg, num: kind }))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn record_pattern_entry(&mut self) -> ParseResult<(Rc<String>, Pattern)> {
|
|
let name = self.identifier()?;
|
|
Ok(match self.token_handler.peek_kind() {
|
|
Colon => {
|
|
expect!(self, Colon);
|
|
let pat = self.pattern()?;
|
|
(name, pat)
|
|
},
|
|
_ => (name.clone(), Pattern::Literal(PatternLiteral::StringPattern(name.clone())))
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn block(&mut self) -> ParseResult<Block> {
|
|
let block = delimited!(self, LCurlyBrace, statement, Newline | Semicolon, RCurlyBrace, nonstrict);
|
|
Ok(block)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn expr_or_block(&mut self) -> ParseResult<Block> {
|
|
match self.token_handler.peek_kind() {
|
|
LCurlyBrace => self.block(),
|
|
_ => {
|
|
let expr = self.expression()?;
|
|
let s = Statement { id: self.id_store.fresh(), kind: StatementKind::Expression(expr) };
|
|
Ok(vec![s])
|
|
}
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn while_expr(&mut self) -> ParseResult<Expression> {
|
|
use self::ExpressionKind::*;
|
|
expect!(self, Keyword(Kw::While));
|
|
let condition = {
|
|
self.restrictions.no_struct_literal = true;
|
|
let x = self.while_cond();
|
|
self.restrictions.no_struct_literal = false;
|
|
x?.map(|expr| bx!(expr))
|
|
};
|
|
let body = self.block()?;
|
|
Ok(Expression::new(self.id_store.fresh(), WhileExpression {condition, body}))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn while_cond(&mut self) -> ParseResult<Option<Expression>> {
|
|
Ok(match self.token_handler.peek_kind() {
|
|
LCurlyBrace => None,
|
|
_ => Some(self.expression()?),
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn for_expr(&mut self) -> ParseResult<Expression> {
|
|
expect!(self, Keyword(Kw::For));
|
|
let enumerators = if let LCurlyBrace = self.token_handler.peek_kind() {
|
|
delimited!(self, LCurlyBrace, enumerator, Comma | Newline, RCurlyBrace)
|
|
} else {
|
|
let single_enum = {
|
|
self.restrictions.no_struct_literal = true;
|
|
let s = self.enumerator();
|
|
self.restrictions.no_struct_literal = false;
|
|
s?
|
|
};
|
|
vec![single_enum]
|
|
};
|
|
let body = Box::new(self.for_expr_body()?);
|
|
Ok(Expression::new(self.id_store.fresh(), ExpressionKind::ForExpression { enumerators, body }))
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn enumerator(&mut self) -> ParseResult<Enumerator> {
|
|
let id = self.identifier()?;
|
|
expect!(self, Operator(ref c) if **c == "<-");
|
|
let generator = self.expression()?;
|
|
Ok(Enumerator { id, generator })
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn for_expr_body(&mut self) -> ParseResult<ForBody> {
|
|
use self::ForBody::*;
|
|
let tok = self.token_handler.peek();
|
|
Ok(match tok.get_kind() {
|
|
LCurlyBrace => {
|
|
let statements = delimited!(self, LCurlyBrace, statement, Newline | Semicolon, RCurlyBrace, nonstrict);
|
|
StatementBlock(statements)
|
|
},
|
|
Keyword(Kw::Return) => {
|
|
self.token_handler.next();
|
|
MonadicReturn(self.expression()?)
|
|
},
|
|
_ => return ParseError::new_with_token("for expressions must end in a block or 'return'", tok),
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn identifier(&mut self) -> ParseResult<Rc<String>> {
|
|
let tok = self.token_handler.next();
|
|
match tok.get_kind() {
|
|
Identifier(s) => Ok(s),
|
|
p => ParseError::new_with_token(format!("Expected an identifier, got {:?}", p), tok),
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn literal(&mut self) -> ParseResult<Expression> {
|
|
use self::ExpressionKind::*;
|
|
|
|
let tok = self.token_handler.peek();
|
|
match tok.get_kind() {
|
|
DigitGroup(_) | HexLiteral(_) | BinNumberSigil | Period => self.number_literal(),
|
|
Keyword(Kw::True) => {
|
|
self.token_handler.next();
|
|
let id = self.id_store.fresh();
|
|
Ok(Expression::new(id, BoolLiteral(true)))
|
|
},
|
|
Keyword(Kw::False) => {
|
|
self.token_handler.next();
|
|
let id = self.id_store.fresh();
|
|
Ok(Expression::new(id, BoolLiteral(false)))
|
|
},
|
|
StrLiteral(s) => {
|
|
self.token_handler.next();
|
|
let id = self.id_store.fresh();
|
|
Ok(Expression::new(id, StringLiteral(s.clone())))
|
|
}
|
|
e => ParseError::new_with_token(format!("Expected a literal expression, got {:?}", e), tok),
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn number_literal(&mut self) -> ParseResult<Expression> {
|
|
match self.token_handler.peek_kind() {
|
|
HexLiteral(_) | BinNumberSigil => self.int_literal(),
|
|
_ => self.float_literal(),
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn int_literal(&mut self) -> ParseResult<Expression> {
|
|
use self::ExpressionKind::*;
|
|
let tok = self.token_handler.next();
|
|
match tok.get_kind() {
|
|
BinNumberSigil => {
|
|
let digits = self.digits()?;
|
|
let n = parse_binary(digits, tok)?;
|
|
Ok(Expression::new(self.id_store.fresh(), NatLiteral(n)))
|
|
},
|
|
HexLiteral(text) => {
|
|
let digits: String = text.chars().filter(|c| c.is_digit(16)).collect();
|
|
let n = parse_hex(digits, tok)?;
|
|
Ok(Expression::new(self.id_store.fresh(), NatLiteral(n)))
|
|
},
|
|
_ => return ParseError::new_with_token("Expected '0x' or '0b'", tok),
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn float_literal(&mut self) -> ParseResult<Expression> {
|
|
use self::ExpressionKind::*;
|
|
let tok = self.token_handler.peek();
|
|
let mut digits = self.digits()?;
|
|
if let Period = self.token_handler.peek_kind() {
|
|
self.token_handler.next();
|
|
digits.push_str(".");
|
|
digits.push_str(&self.digits()?);
|
|
match digits.parse::<f64>() {
|
|
Ok(f) => Ok(Expression::new(self.id_store.fresh(), FloatLiteral(f))),
|
|
Err(e) => ParseError::new_with_token(format!("Float failed to parse with error: {}", e), tok),
|
|
|
|
}
|
|
} else {
|
|
match digits.parse::<u64>() {
|
|
Ok(d) => Ok(Expression::new(self.id_store.fresh(), NatLiteral(d))),
|
|
Err(e) => ParseError::new_with_token(format!("Integer failed to parse with error: {}", e), tok),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn digits(&mut self) -> ParseResult<String> {
|
|
let mut ds = String::new();
|
|
loop {
|
|
match self.token_handler.peek_kind() {
|
|
Underscore => { self.token_handler.next(); continue; },
|
|
DigitGroup(ref s) => { self.token_handler.next(); ds.push_str(s)},
|
|
_ => break,
|
|
}
|
|
}
|
|
Ok(ds)
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn import_declaration(&mut self) -> ParseResult<ImportSpecifier> {
|
|
expect!(self, Keyword(Import));
|
|
let mut path_components = vec![];
|
|
path_components.push(self.identifier()?);
|
|
loop {
|
|
match (self.token_handler.peek_kind(), self.token_handler.peek_kind_n(1)) {
|
|
(Colon, Colon) => {
|
|
self.token_handler.next(); self.token_handler.next();
|
|
if let Identifier(_) = self.token_handler.peek_kind() {
|
|
path_components.push(self.identifier()?);
|
|
} else {
|
|
break;
|
|
}
|
|
},
|
|
_ => break,
|
|
}
|
|
}
|
|
|
|
let imported_names = match self.token_handler.peek_kind() {
|
|
LCurlyBrace => {
|
|
let names = delimited!(self, LCurlyBrace, identifier, Comma, RCurlyBrace);
|
|
ImportedNames::List(names)
|
|
},
|
|
Operator(ref s) if **s == "*" => {
|
|
self.token_handler.next();
|
|
ImportedNames::All
|
|
},
|
|
_ => ImportedNames::LastOfPath
|
|
};
|
|
|
|
Ok(ImportSpecifier {
|
|
id: self.id_store.fresh(),
|
|
path_components,
|
|
imported_names
|
|
})
|
|
}
|
|
|
|
#[recursive_descent_method]
|
|
fn import_suffix(&mut self) -> ParseResult<ImportedNames> {
|
|
Ok(match self.token_handler.peek_kind() {
|
|
Operator(ref s) if **s == "*" => {
|
|
self.token_handler.next();
|
|
ImportedNames::All
|
|
},
|
|
LCurlyBrace => {
|
|
let names = delimited!(self, LCurlyBrace, identifier, Comma, RCurlyBrace);
|
|
ImportedNames::List(names)
|
|
},
|
|
_ => return ParseError::new_with_token("Expected '{{' or '*'", self.token_handler.peek()),
|
|
})
|
|
}
|
|
}
|
|
|
|
fn parse_binary(digits: String, tok: Token) -> ParseResult<u64> {
|
|
let mut result: u64 = 0;
|
|
let mut multiplier = 1;
|
|
for d in digits.chars().rev() {
|
|
match d {
|
|
'1' => result += multiplier,
|
|
'0' => (),
|
|
_ => return ParseError::new_with_token("Encountered a character not '1' or '0 while parsing a binary literal", tok),
|
|
}
|
|
multiplier = match multiplier.checked_mul(2) {
|
|
Some(m) => m,
|
|
None => return ParseError::new_with_token("This binary expression will overflow", tok)
|
|
}
|
|
}
|
|
Ok(result)
|
|
}
|
|
|
|
fn parse_hex(digits: String, tok: Token) -> ParseResult<u64> {
|
|
let mut result: u64 = 0;
|
|
let mut multiplier: u64 = 1;
|
|
for d in digits.chars().rev() {
|
|
match d.to_digit(16) {
|
|
Some(n) => result += n as u64 * multiplier,
|
|
None => return ParseError::new_with_token("Encountered a non-hex digit in a hex literal", tok),
|
|
}
|
|
multiplier = match multiplier.checked_mul(16) {
|
|
Some(m) => m,
|
|
None => return ParseError::new_with_token("This hex expression will overflow", tok)
|
|
}
|
|
}
|
|
Ok(result)
|
|
}
|
|
|