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Some cleanups in Parser

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-get rid of some use statements
-mkae error messages better
This commit is contained in:
greg 2017-01-04 19:30:44 -08:00
parent e888e82404
commit 761500b9d6
1 changed files with 5 additions and 18 deletions
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23
src/parser.rs
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@ -1,5 +1,6 @@
use std::fmt;
use tokenizer::{Token, Kw, Op};
use tokenizer::Token::*;
use std::collections::VecDeque;
use std::rc::Rc;
@ -139,7 +140,7 @@ macro_rules! expect {
match $self_.peek() {
Some($token) => {$self_.next();},
Some(x) => {
let err = format!("Expected `{:?}` but got `{:?}`", stringify!($token), x); //TODO implement Display for token
let err = format!("Expected `{:?}` but got `{:?}`", stringify!($token), x);
return ParseError::result_from_str(&err)
},
None => {
@ -155,13 +156,13 @@ macro_rules! expect_identifier {
($self_:expr) => {
match $self_.peek() {
Some(Identifier(s)) => {$self_.next(); s},
_ => return ParseError::result_from_str("Expected Identifier")
Some(x) => return ParseError::result_from_str(&format!("Expected identifier, but got {:?}", x)),
None => return ParseError::result_from_str("Expected identifier, but got end of input"),
}
}
}
fn is_delimiter(token: &Token) -> bool {
use tokenizer::Token::*;
match *token {
Newline | Semicolon => true,
_ => false,
@ -190,23 +191,19 @@ impl Parser {
}
}
}
Ok(ast)
}
fn statement(&mut self) -> ParseResult<Statement> {
use tokenizer::Token::*;
let node: Statement = match self.peek() {
Some(Keyword(Kw::Fn)) => try!(self.declaration()),
Some(_) => Statement::ExprNode(try!(self.expression())),
None => panic!("unexpected end of tokens"),
None => panic!("Unexpected end of tokens"),
};
Ok(node)
}
fn declaration(&mut self) -> ParseResult<Statement> {
use tokenizer::Token::*;
expect!(self, Keyword(Kw::Fn));
let prototype = try!(self.prototype());
let body: Vec<Statement> = try!(self.body());
@ -218,7 +215,6 @@ impl Parser {
}
fn prototype(&mut self) -> ParseResult<Prototype> {
use tokenizer::Token::*;
let name: Rc<String> = expect_identifier!(self);
expect!(self, LParen);
let parameters: Vec<Rc<String>> = try!(self.identlist());
@ -230,7 +226,6 @@ impl Parser {
}
fn identlist(&mut self) -> ParseResult<Vec<Rc<String>>> {
use tokenizer::Token::*;
let mut args: Vec<Rc<String>> = Vec::new();
while let Some(Identifier(name)) = self.peek() {
args.push(name.clone());
@ -245,7 +240,6 @@ impl Parser {
}
fn exprlist(&mut self) -> ParseResult<Vec<Expression>> {
use tokenizer::Token::*;
let mut args: Vec<Expression> = Vec::new();
loop {
if let Some(RParen) = self.peek() {
@ -263,7 +257,6 @@ impl Parser {
}
fn body(&mut self) -> ParseResult<Vec<Statement>> {
use tokenizer::Token::*;
let mut statements = Vec::new();
loop {
match self.peek() {
@ -290,7 +283,6 @@ impl Parser {
mut lhs: Expression,
min_precedence: u8)
-> ParseResult<Expression> {
use tokenizer::Token::*;
while let Some(Operator(op)) = self.peek() {
let precedence = self.get_precedence(&op);
if precedence < min_precedence {
@ -315,7 +307,6 @@ impl Parser {
}
fn primary_expression(&mut self) -> ParseResult<Expression> {
use tokenizer::Token::*;
Ok(match self.peek() {
Some(Keyword(Kw::Null)) => {
self.next();
@ -343,7 +334,6 @@ impl Parser {
}
fn while_expr(&mut self) -> ParseResult<Expression> {
use tokenizer::Token::*;
use self::Expression::*;
expect!(self, Keyword(Kw::While));
@ -370,7 +360,6 @@ impl Parser {
}
fn conditional_expr(&mut self) -> ParseResult<Expression> {
use tokenizer::Token::*;
use self::Expression::*;
expect!(self, Keyword(Kw::If));
@ -431,7 +420,6 @@ impl Parser {
}
fn identifier_expr(&mut self) -> ParseResult<Expression> {
use tokenizer::Token::*;
let name = expect_identifier!(self);
let expr = match self.peek() {
Some(LParen) => {
@ -445,7 +433,6 @@ impl Parser {
}
fn call_expr(&mut self) -> ParseResult<Vec<Expression>> {
use tokenizer::Token::*;
expect!(self, LParen);
let args: Vec<Expression> = try!(self.exprlist());
expect!(self, RParen);