Move some parsing code around
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greg
parent
7d68b2a05a
commit
82502ad0ad
@ -10,124 +10,6 @@ use ast::*;
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use builtin::{BinOp, PrefixOp};
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/* Schala EBNF Grammar */
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/* Terminal productions are in 'single quotes' or UPPERCASE if they are a class
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* or not representable in ASCII
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/* Top-level Structure */
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program := (statement delimiter)* EOF
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delimiter := NEWLINE | ';'
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statement := expression | declaration
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block := '{' (statement delimiter)* '}'
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declaration := type_declaration | func_declaration | binding_declaration | impl_declaration
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/* Declarations - Types */
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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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/* Declaration - Functions */
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func_declaration := func_signature func_body
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func_body := ε | '{' (statement delimiter)* '}'
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func_signature := 'fn' IDENTIFIER formal_param_list func_body
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formal_param_list := '(' (formal_param ',')* ')'
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formal_param := IDENTIFIER type_anno+
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/* Declaration - Variable bindings */
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binding_declaration := 'let' 'mut'? IDENTIFIER '=' expresion
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/* Declaration - Interface */
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interface_declaration := 'interface' interface_name signature_block
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impl_declaration := 'impl' IDENTIFIER decl_block | 'impl' interface_name 'for' IDENTIFIER decl_block
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decl_block := '{' (func_declaration)* '}'
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signature_block := '{' (func_signature)* '}'
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interface_name := IDENTIFIER
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/* Type annotations */
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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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/* Expressions */
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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 ( '(' expr_list ')' )*
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expr_list := expression (',' expression)* | ε
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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 | curly_brace_expr | list_expr
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/* Primary Expressions */
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curly_brace_expr := lambda_expr | anonymous_struct //TODO
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list_expr := '[' (expression, ',')* ']'
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lambda_expr := '{' '|' (formal_param ',')* '|' (type_anno)* (statement delimiter)* '}'
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paren_expr := LParen paren_inner RParen
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paren_inner := (expression ',')*
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identifier_expr := named_struct | IDENTIFIER
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/* Expression - Literals */
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literal := 'true' | 'false' | number_literal | STR_LITERAL
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named_struct := 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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// a float_literal can still be assigned to an int in type-checking
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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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/* Pattern syntax */
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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' | number_literal | STR_LITERAL | IDENTIFIER
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record_pattern := IDENTIFIER '{' (record_pattern_entry, ',')* '}'
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record_pattern_entry := IDENTIFIER | IDENTIFIER ':' Pattern
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tuple_struct_pattern := IDENTIFIER '(' (pattern, ',')* ')'
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/* Expression - If */
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if_expr := 'if' discriminator ('then' condititional | 'is' simple_pattern_match | guard_block)
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discriminator := modified_precedence_expression
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modified_precedence_expression := precedence_expr (operator)+ //TODO this is currently hard, rearchitect things
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conditional := block else_clause
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simple_pattern_match := pattern 'then' conditional
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else_clause := ε | 'else' block
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guard_block := '{' (guard_arm, ',')* '}'
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guard_arm := guard '->' block
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guard := 'is' pattern | (operator)+ precedence_expr
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/* Expression - While */
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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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//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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/* Expression - For */
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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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type TokenIter = Peekable<IntoIter<Token>>;
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#[derive(Debug)]
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@ -265,6 +147,123 @@ macro_rules! delimited {
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};
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}
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/* Schala EBNF Grammar */
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/* Terminal productions are in 'single quotes' or UPPERCASE if they are a class
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* or not representable in ASCII
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/* Top-level Structure */
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program := (statement delimiter)* EOF
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delimiter := NEWLINE | ';'
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statement := expression | declaration
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block := '{' (statement delimiter)* '}'
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declaration := type_declaration | func_declaration | binding_declaration | impl_declaration
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/* Declarations - Types */
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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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/* Declaration - Functions */
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func_declaration := func_signature func_body
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func_body := ε | '{' (statement delimiter)* '}'
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func_signature := 'fn' IDENTIFIER formal_param_list func_body
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formal_param_list := '(' (formal_param ',')* ')'
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formal_param := IDENTIFIER type_anno+
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/* Declaration - Variable bindings */
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binding_declaration := 'let' 'mut'? IDENTIFIER '=' expresion
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/* Declaration - Interface */
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interface_declaration := 'interface' interface_name signature_block
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impl_declaration := 'impl' IDENTIFIER decl_block | 'impl' interface_name 'for' IDENTIFIER decl_block
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decl_block := '{' (func_declaration)* '}'
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signature_block := '{' (func_signature)* '}'
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interface_name := IDENTIFIER
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/* Type annotations */
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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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/* Expressions */
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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 ( '(' expr_list ')' )*
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expr_list := expression (',' expression)* | ε
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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 | curly_brace_expr | list_expr
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/* Primary Expressions */
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curly_brace_expr := lambda_expr | anonymous_struct //TODO
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list_expr := '[' (expression, ',')* ']'
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lambda_expr := '{' '|' (formal_param ',')* '|' (type_anno)* (statement delimiter)* '}'
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paren_expr := LParen paren_inner RParen
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paren_inner := (expression ',')*
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identifier_expr := named_struct | IDENTIFIER
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/* Expression - Literals */
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literal := 'true' | 'false' | number_literal | STR_LITERAL
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named_struct := 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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// a float_literal can still be assigned to an int in type-checking
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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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/* Pattern syntax */
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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' | number_literal | STR_LITERAL | IDENTIFIER
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record_pattern := IDENTIFIER '{' (record_pattern_entry, ',')* '}'
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record_pattern_entry := IDENTIFIER | IDENTIFIER ':' Pattern
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tuple_struct_pattern := IDENTIFIER '(' (pattern, ',')* ')'
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/* Expression - If */
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if_expr := 'if' discriminator ('then' condititional | 'is' simple_pattern_match | guard_block)
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discriminator := modified_precedence_expression
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modified_precedence_expression := precedence_expr (operator)+ //TODO this is currently hard, rearchitect things
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conditional := block else_clause
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simple_pattern_match := pattern 'then' conditional
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else_clause := ε | 'else' block
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guard_block := '{' (guard_arm, ',')* '}'
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guard_arm := guard '->' block
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guard := 'is' pattern | (operator)+ precedence_expr
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/* Expression - While */
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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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//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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/* Expression - For */
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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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impl Parser {
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parse_method!(program(&mut self) -> ParseResult<AST> {
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let mut statements = Vec::new();
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