2016-02-29 22:43:45 +01:00
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use std::error::Error;
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use std::fmt;
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use std::iter::Peekable;
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use std::str::Chars;
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2016-03-02 14:37:28 +01:00
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use std::char;
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2016-02-29 22:43:45 +01:00
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2016-03-02 15:16:36 +01:00
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#[derive(Debug)]
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pub enum LexError {
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UnexpectedChar,
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MalformedEscapeSequence,
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2016-04-14 03:40:06 +02:00
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MalformedNumber,
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2016-04-17 04:32:18 +02:00
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MalformedChar,
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2016-03-02 15:16:36 +01:00
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}
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impl Error for LexError {
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fn description(&self) -> &str {
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match *self {
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LexError::UnexpectedChar => "Unexpected character in input",
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LexError::MalformedEscapeSequence => "Unexpected values in escape sequence",
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2016-04-14 03:40:06 +02:00
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LexError::MalformedNumber => "Unexpected characters in number",
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2016-04-17 04:32:18 +02:00
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LexError::MalformedChar => "Char constant not a single character",
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2016-03-02 15:16:36 +01:00
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}
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}
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fn cause(&self) -> Option<&Error> {
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None
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}
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}
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impl fmt::Display for LexError {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "{}", self.description())
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}
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}
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2016-02-29 22:43:45 +01:00
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#[derive(Debug)]
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pub enum ParseError {
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BadInput,
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InputPastEndOfFile,
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UnknownOperator,
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MissingRParen,
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MissingLCurly,
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MissingRCurly,
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2016-03-26 18:46:28 +01:00
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MissingRSquare,
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2016-02-29 22:43:45 +01:00
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MalformedCallExpr,
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2016-03-26 18:46:28 +01:00
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MalformedIndexExpr,
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2016-03-01 21:16:10 +01:00
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VarExpectsIdentifier,
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FnMissingName,
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2016-04-17 04:32:18 +02:00
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FnMissingParams,
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2016-02-29 22:43:45 +01:00
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}
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impl Error for ParseError {
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fn description(&self) -> &str {
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match *self {
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ParseError::BadInput => "Unparseable characters in the input stream",
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ParseError::InputPastEndOfFile => "Input past end of file",
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ParseError::UnknownOperator => "Unknown operator",
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ParseError::MissingRParen => "Expected ')'",
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ParseError::MissingLCurly => "Expected '{'",
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ParseError::MissingRCurly => "Expected '}'",
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2016-03-26 18:46:28 +01:00
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ParseError::MissingRSquare => "Expected ']'",
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2016-02-29 22:43:45 +01:00
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ParseError::MalformedCallExpr => "Call contains bad expression",
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2016-03-26 18:46:28 +01:00
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ParseError::MalformedIndexExpr => "Indexing expression missing correct index",
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2016-03-01 21:16:10 +01:00
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ParseError::VarExpectsIdentifier => "'var' expects the name of a variable",
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ParseError::FnMissingName => "Function declaration is missing name",
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2016-04-17 04:32:18 +02:00
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ParseError::FnMissingParams => "Function declaration is missing parameters",
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2016-02-29 22:43:45 +01:00
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}
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}
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2017-10-14 19:46:22 +02:00
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fn cause(&self) -> Option<&Error> { None }
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2016-02-29 22:43:45 +01:00
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}
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impl fmt::Display for ParseError {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "{}", self.description())
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}
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}
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2016-03-01 21:16:10 +01:00
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#[derive(Debug, Clone)]
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pub struct FnDef {
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pub name: String,
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pub params: Vec<String>,
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2016-04-17 04:32:18 +02:00
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pub body: Box<Stmt>,
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2016-03-01 21:16:10 +01:00
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}
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#[derive(Debug, Clone)]
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2016-04-17 04:32:18 +02:00
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pub enum Stmt {
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If(Box<Expr>, Box<Stmt>),
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IfElse(Box<Expr>, Box<Stmt>, Box<Stmt>),
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While(Box<Expr>, Box<Stmt>),
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Var(String, Option<Box<Expr>>),
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2017-10-02 23:44:45 +02:00
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Block(Vec<Stmt>),
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2016-04-17 04:32:18 +02:00
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Expr(Box<Expr>),
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Break,
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Return,
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ReturnWithVal(Box<Expr>),
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}
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2016-02-29 22:43:45 +01:00
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2016-03-01 21:16:10 +01:00
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#[derive(Debug, Clone)]
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2016-04-17 04:32:18 +02:00
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pub enum Expr {
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IntConst(i64),
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Identifier(String),
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CharConst(char),
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StringConst(String),
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2017-10-02 23:44:45 +02:00
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FnCall(String, Vec<Expr>),
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2016-04-17 04:32:18 +02:00
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Assignment(Box<Expr>, Box<Expr>),
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Dot(Box<Expr>, Box<Expr>),
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Index(String, Box<Expr>),
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2017-10-02 23:44:45 +02:00
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Array(Vec<Expr>),
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2016-04-17 04:32:18 +02:00
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True,
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False,
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}
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2016-02-29 22:43:45 +01:00
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#[derive(Debug)]
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2016-04-17 04:32:18 +02:00
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pub enum Token {
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IntConst(i64),
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Identifier(String),
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CharConst(char),
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StringConst(String),
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LCurly,
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RCurly,
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LParen,
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RParen,
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LSquare,
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RSquare,
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Plus,
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Minus,
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Multiply,
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Divide,
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Semicolon,
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Colon,
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Comma,
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Period,
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Equals,
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True,
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False,
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Var,
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If,
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Else,
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While,
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LessThan,
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GreaterThan,
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Bang,
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LessThanEqual,
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GreaterThanEqual,
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EqualTo,
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NotEqualTo,
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Pipe,
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Or,
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Ampersand,
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And,
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Fn,
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Break,
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Return,
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LexErr(LexError),
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}
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2016-02-29 22:43:45 +01:00
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pub struct TokenIterator<'a> {
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2016-04-17 04:32:18 +02:00
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char_stream: Peekable<Chars<'a>>,
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}
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impl<'a> TokenIterator<'a> {
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pub fn parse_string_const(&mut self, enclosing_char: char) -> Result<String, LexError> {
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let mut result = Vec::new();
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let mut escape = false;
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while let Some(nxt) = self.char_stream.next() {
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match nxt {
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'\\' if !escape => escape = true,
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'\\' if escape => {
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escape = false;
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result.push('\\');
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}
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't' if escape => {
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escape = false;
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result.push('\t');
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}
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'n' if escape => {
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escape = false;
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result.push('\n');
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}
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'r' if escape => {
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escape = false;
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result.push('\r');
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}
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'x' if escape => {
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escape = false;
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let mut out_val: u32 = 0;
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for _ in 0..2 {
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if let Some(c) = self.char_stream.next() {
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if let Some(d1) = c.to_digit(16) {
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out_val *= 16;
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out_val += d1;
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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}
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if let Some(r) = char::from_u32(out_val) {
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result.push(r);
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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}
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'u' if escape => {
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escape = false;
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let mut out_val: u32 = 0;
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for _ in 0..4 {
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if let Some(c) = self.char_stream.next() {
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if let Some(d1) = c.to_digit(16) {
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out_val *= 16;
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out_val += d1;
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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}
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if let Some(r) = char::from_u32(out_val) {
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result.push(r);
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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}
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'U' if escape => {
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escape = false;
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let mut out_val: u32 = 0;
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for _ in 0..8 {
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if let Some(c) = self.char_stream.next() {
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if let Some(d1) = c.to_digit(16) {
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out_val *= 16;
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out_val += d1;
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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}
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if let Some(r) = char::from_u32(out_val) {
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result.push(r);
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} else {
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return Err(LexError::MalformedEscapeSequence);
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}
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}
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x if enclosing_char == x && escape => result.push(x),
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x if enclosing_char == x && !escape => break,
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_ if escape => return Err(LexError::MalformedEscapeSequence),
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_ => {
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escape = false;
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result.push(nxt);
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}
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}
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}
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let out: String = result.iter().cloned().collect();
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Ok(out)
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}
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2016-02-29 22:43:45 +01:00
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}
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impl<'a> Iterator for TokenIterator<'a> {
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type Item = Token;
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fn next(&mut self) -> Option<Self::Item> {
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while let Some(c) = self.char_stream.next() {
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match c {
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'0'...'9' => {
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let mut result = Vec::new();
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result.push(c);
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while let Some(&nxt) = self.char_stream.peek() {
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match nxt {
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2016-04-17 04:32:18 +02:00
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'0'...'9' => {
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result.push(nxt);
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self.char_stream.next();
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}
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_ => break,
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2016-02-29 22:43:45 +01:00
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}
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}
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2016-04-17 04:32:18 +02:00
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let out: String = result.iter().cloned().collect();
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2016-02-29 22:43:45 +01:00
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2016-04-13 04:52:27 +02:00
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if let Ok(val) = out.parse::<i64>() {
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2016-03-02 14:37:28 +01:00
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return Some(Token::IntConst(val));
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2016-02-29 22:43:45 +01:00
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}
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2016-03-02 15:16:36 +01:00
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return Some(Token::LexErr(LexError::MalformedNumber));
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2016-04-17 04:32:18 +02:00
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}
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2016-02-29 22:43:45 +01:00
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'A'...'Z' | 'a'...'z' | '_' => {
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let mut result = Vec::new();
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result.push(c);
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while let Some(&nxt) = self.char_stream.peek() {
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match nxt {
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2017-10-14 19:46:22 +02:00
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x if x.is_alphanumeric() || x == '_' => {
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result.push(x);
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2016-04-17 04:32:18 +02:00
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self.char_stream.next();
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}
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_ => break,
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2016-02-29 22:43:45 +01:00
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}
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}
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2016-04-17 04:32:18 +02:00
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let out: String = result.iter().cloned().collect();
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2016-02-29 22:43:45 +01:00
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2017-10-14 19:46:22 +02:00
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match out.as_ref() {
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"true" => return Some(Token::True),
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"false" => return Some(Token::False),
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"let" => return Some(Token::Var),
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"if" => return Some(Token::If),
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"else" => return Some(Token::Else),
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"while" => return Some(Token::While),
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"break" => return Some(Token::Break),
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"return" => return Some(Token::Return),
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"fn" => return Some(Token::Fn),
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x => return Some(Token::Identifier(x.to_string()))
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2016-02-29 22:43:45 +01:00
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}
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2016-04-17 04:32:18 +02:00
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}
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2016-03-02 14:37:28 +01:00
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'"' => {
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2016-04-17 04:32:18 +02:00
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match self.parse_string_const('"') {
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Ok(out) => return Some(Token::StringConst(out)),
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Err(e) => return Some(Token::LexErr(e)),
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2016-03-02 14:37:28 +01:00
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}
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}
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2016-04-14 03:40:06 +02:00
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'\'' => {
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2016-04-17 04:32:18 +02:00
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match self.parse_string_const('\'') {
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Ok(result) => {
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let mut chars = result.chars();
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if let Some(out) = chars.next() {
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println!("result: {}", result);
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if chars.count() != 0 {
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return Some(Token::LexErr(LexError::MalformedChar));
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2016-04-14 03:40:06 +02:00
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}
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2016-04-17 04:32:18 +02:00
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return Some(Token::CharConst(out));
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} else {
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return Some(Token::LexErr(LexError::MalformedChar));
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2016-04-14 03:40:06 +02:00
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}
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}
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2016-04-17 04:32:18 +02:00
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Err(e) => return Some(Token::LexErr(e)),
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2016-04-14 03:40:06 +02:00
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}
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}
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2017-10-14 19:46:22 +02:00
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'{' => return Some(Token::LCurly),
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'}' => return Some(Token::RCurly),
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'(' => return Some(Token::LParen),
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|
|
|
')' => return Some(Token::RParen),
|
|
|
|
'[' => return Some(Token::LSquare),
|
|
|
|
']' => return Some(Token::RSquare),
|
|
|
|
'+' => return Some(Token::Plus),
|
|
|
|
'-' => return Some(Token::Minus),
|
|
|
|
'*' => return Some(Token::Multiply),
|
|
|
|
'/' => return Some(Token::Divide),
|
|
|
|
';' => return Some(Token::Semicolon),
|
|
|
|
':' => return Some(Token::Colon),
|
|
|
|
',' => return Some(Token::Comma),
|
|
|
|
'.' => return Some(Token::Period),
|
2016-04-14 03:01:08 +02:00
|
|
|
'=' => {
|
2016-03-01 15:40:48 +01:00
|
|
|
match self.char_stream.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&'=') => {
|
|
|
|
self.char_stream.next();
|
|
|
|
return Some(Token::EqualTo);
|
|
|
|
}
|
2017-10-14 19:46:22 +02:00
|
|
|
_ => return Some(Token::Equals),
|
2016-03-01 15:40:48 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2016-04-14 03:01:08 +02:00
|
|
|
'<' => {
|
2016-03-01 15:40:48 +01:00
|
|
|
match self.char_stream.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&'=') => {
|
|
|
|
self.char_stream.next();
|
|
|
|
return Some(Token::LessThanEqual);
|
|
|
|
}
|
2017-10-14 19:46:22 +02:00
|
|
|
_ => return Some(Token::LessThan),
|
2016-03-01 15:40:48 +01:00
|
|
|
}
|
|
|
|
}
|
2016-04-14 03:01:08 +02:00
|
|
|
'>' => {
|
2016-03-01 15:40:48 +01:00
|
|
|
match self.char_stream.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&'=') => {
|
|
|
|
self.char_stream.next();
|
|
|
|
return Some(Token::GreaterThanEqual);
|
|
|
|
}
|
2017-10-14 19:46:22 +02:00
|
|
|
_ => return Some(Token::GreaterThan),
|
2016-03-01 15:40:48 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2016-04-14 03:01:08 +02:00
|
|
|
'!' => {
|
2016-03-01 15:40:48 +01:00
|
|
|
match self.char_stream.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&'=') => {
|
|
|
|
self.char_stream.next();
|
|
|
|
return Some(Token::NotEqualTo);
|
|
|
|
}
|
2017-10-14 19:46:22 +02:00
|
|
|
_ => return Some(Token::Bang),
|
2016-03-01 15:40:48 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2016-04-14 03:01:08 +02:00
|
|
|
'|' => {
|
2016-03-01 15:40:48 +01:00
|
|
|
match self.char_stream.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&'|') => {
|
|
|
|
self.char_stream.next();
|
|
|
|
return Some(Token::Or);
|
|
|
|
}
|
2017-10-14 19:46:22 +02:00
|
|
|
_ => return Some(Token::Pipe),
|
2016-03-01 15:40:48 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2016-04-14 03:01:08 +02:00
|
|
|
'&' => {
|
2016-03-01 15:40:48 +01:00
|
|
|
match self.char_stream.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&'&') => {
|
|
|
|
self.char_stream.next();
|
|
|
|
return Some(Token::And);
|
|
|
|
}
|
2017-10-14 19:46:22 +02:00
|
|
|
_ => return Some(Token::Ampersand),
|
2016-03-01 15:40:48 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2017-10-02 08:33:47 +02:00
|
|
|
_x if _x.is_whitespace() => (),
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => return Some(Token::LexErr(LexError::UnexpectedChar)),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
None
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2017-10-02 23:44:45 +02:00
|
|
|
pub fn lex(input: &str) -> TokenIterator {
|
2016-02-29 22:43:45 +01:00
|
|
|
TokenIterator { char_stream: input.chars().peekable() }
|
|
|
|
}
|
|
|
|
|
|
|
|
fn get_precedence(token: &Token) -> i32 {
|
|
|
|
match *token {
|
|
|
|
Token::Equals => 10,
|
2016-03-01 15:40:48 +01:00
|
|
|
Token::Or => 11,
|
|
|
|
Token::And => 12,
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::LessThan
|
|
|
|
| Token::LessThanEqual
|
|
|
|
| Token::GreaterThan
|
|
|
|
| Token::GreaterThanEqual
|
|
|
|
| Token::EqualTo
|
|
|
|
| Token::NotEqualTo => 15,
|
|
|
|
Token::Plus
|
|
|
|
| Token::Minus => 20,
|
|
|
|
Token::Divide
|
|
|
|
| Token::Multiply => 40,
|
2016-03-07 21:39:02 +01:00
|
|
|
Token::Period => 100,
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => -1,
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_paren_expr<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
|
|
|
|
let expr = try!(parse_expr(input));
|
|
|
|
|
|
|
|
match input.next() {
|
|
|
|
Some(Token::RParen) => Ok(expr),
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => Err(ParseError::MissingRParen),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
fn parse_call_expr<'a>(id: String,
|
|
|
|
input: &mut Peekable<TokenIterator<'a>>)
|
|
|
|
-> Result<Expr, ParseError> {
|
2016-02-29 22:43:45 +01:00
|
|
|
let mut args = Vec::new();
|
2017-10-02 23:44:45 +02:00
|
|
|
|
|
|
|
if let Some(&Token::RParen) = input.peek() {
|
|
|
|
input.next();
|
|
|
|
return Ok(Expr::FnCall(id, args));
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
loop {
|
|
|
|
if let Ok(arg) = parse_expr(input) {
|
|
|
|
args.push(arg);
|
2016-04-17 04:32:18 +02:00
|
|
|
} else {
|
2016-02-29 22:43:45 +01:00
|
|
|
return Err(ParseError::MalformedCallExpr);
|
|
|
|
}
|
|
|
|
|
|
|
|
match input.peek() {
|
2016-03-01 21:16:10 +01:00
|
|
|
Some(&Token::RParen) => {
|
|
|
|
input.next();
|
2017-10-02 23:44:45 +02:00
|
|
|
return Ok(Expr::FnCall(id, args));
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2016-02-29 22:43:45 +01:00
|
|
|
Some(&Token::Comma) => (),
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => return Err(ParseError::MalformedCallExpr),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
input.next();
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
fn parse_index_expr<'a>(id: String,
|
|
|
|
input: &mut Peekable<TokenIterator<'a>>)
|
|
|
|
-> Result<Expr, ParseError> {
|
2016-03-26 18:46:28 +01:00
|
|
|
if let Ok(idx) = parse_expr(input) {
|
|
|
|
match input.peek() {
|
|
|
|
Some(&Token::RSquare) => {
|
|
|
|
input.next();
|
2016-04-17 04:32:18 +02:00
|
|
|
return Ok(Expr::Index(id, Box::new(idx)));
|
|
|
|
}
|
|
|
|
_ => return Err(ParseError::MalformedIndexExpr),
|
2016-03-26 18:46:28 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
} else {
|
2016-03-26 18:46:28 +01:00
|
|
|
return Err(ParseError::MalformedIndexExpr);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
fn parse_ident_expr<'a>(id: String,
|
|
|
|
input: &mut Peekable<TokenIterator<'a>>)
|
|
|
|
-> Result<Expr, ParseError> {
|
2016-03-26 18:46:28 +01:00
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::LParen) => {
|
|
|
|
input.next();
|
|
|
|
parse_call_expr(id, input)
|
|
|
|
}
|
|
|
|
Some(&Token::LSquare) => {
|
|
|
|
input.next();
|
|
|
|
parse_index_expr(id, input)
|
|
|
|
}
|
2017-10-02 23:44:45 +02:00
|
|
|
_ => Ok(Expr::Identifier(id)),
|
2016-03-26 18:46:28 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_array_expr<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
|
|
|
|
let mut arr = Vec::new();
|
|
|
|
|
|
|
|
let skip_contents = match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::RSquare) => true,
|
|
|
|
_ => false,
|
2016-03-26 18:46:28 +01:00
|
|
|
};
|
|
|
|
|
|
|
|
if !skip_contents {
|
|
|
|
while let Some(_) = input.peek() {
|
|
|
|
arr.push(try!(parse_expr(input)));
|
2017-10-02 23:44:45 +02:00
|
|
|
if let Some(&Token::Comma) = input.peek() {
|
|
|
|
input.next();
|
2016-03-26 18:46:28 +01:00
|
|
|
}
|
|
|
|
|
2017-10-02 23:44:45 +02:00
|
|
|
if let Some(&Token::RSquare) = input.peek() { break }
|
2016-04-14 03:01:08 +02:00
|
|
|
}
|
2016-03-26 18:46:28 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::RSquare) => {
|
|
|
|
input.next();
|
2017-10-02 23:44:45 +02:00
|
|
|
Ok(Expr::Array(arr))
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
|
|
|
_ => Err(ParseError::MissingRSquare),
|
2016-03-26 18:46:28 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
}
|
|
|
|
|
2016-02-29 22:43:45 +01:00
|
|
|
fn parse_primary<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
|
|
|
|
if let Some(token) = input.next() {
|
|
|
|
match token {
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::IntConst(ref x) => Ok(Expr::IntConst(*x)),
|
2016-04-17 04:32:18 +02:00
|
|
|
Token::StringConst(ref s) => Ok(Expr::StringConst(s.clone())),
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::CharConst(ref c) => Ok(Expr::CharConst(*c)),
|
2016-04-17 04:32:18 +02:00
|
|
|
Token::Identifier(ref s) => parse_ident_expr(s.clone(), input),
|
|
|
|
Token::LParen => parse_paren_expr(input),
|
|
|
|
Token::LSquare => parse_array_expr(input),
|
|
|
|
Token::True => Ok(Expr::True),
|
|
|
|
Token::False => Ok(Expr::False),
|
|
|
|
Token::LexErr(le) => {
|
|
|
|
println!("Error: {}", le);
|
|
|
|
Err(ParseError::BadInput)
|
|
|
|
}
|
|
|
|
_ => {
|
|
|
|
println!("Can't parse: {:?}", token);
|
|
|
|
Err(ParseError::BadInput)
|
|
|
|
}
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
} else {
|
2016-02-29 22:43:45 +01:00
|
|
|
Err(ParseError::InputPastEndOfFile)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
fn parse_binop<'a>(input: &mut Peekable<TokenIterator<'a>>,
|
|
|
|
prec: i32,
|
|
|
|
lhs: Expr)
|
|
|
|
-> Result<Expr, ParseError> {
|
2016-02-29 22:43:45 +01:00
|
|
|
let mut lhs_curr = lhs;
|
|
|
|
|
|
|
|
loop {
|
|
|
|
let mut curr_prec = -1;
|
|
|
|
|
2016-04-14 03:01:08 +02:00
|
|
|
if let Some(curr_op) = input.peek() {
|
2016-02-29 22:43:45 +01:00
|
|
|
curr_prec = get_precedence(curr_op);
|
|
|
|
}
|
|
|
|
|
|
|
|
if curr_prec < prec {
|
|
|
|
return Ok(lhs_curr);
|
|
|
|
}
|
|
|
|
|
|
|
|
if let Some(op_token) = input.next() {
|
|
|
|
let mut rhs = try!(parse_primary(input));
|
|
|
|
|
|
|
|
let mut next_prec = -1;
|
2016-04-14 03:01:08 +02:00
|
|
|
|
2016-02-29 22:43:45 +01:00
|
|
|
if let Some(next_op) = input.peek() {
|
|
|
|
next_prec = get_precedence(next_op);
|
|
|
|
}
|
|
|
|
|
|
|
|
if curr_prec < next_prec {
|
2016-04-17 04:32:18 +02:00
|
|
|
rhs = try!(parse_binop(input, curr_prec + 1, rhs));
|
|
|
|
} else if curr_prec >= 100 {
|
|
|
|
// Always bind right to left for precedence over 100
|
2016-04-14 03:01:08 +02:00
|
|
|
rhs = try!(parse_binop(input, curr_prec, rhs));
|
2016-03-07 21:39:02 +01:00
|
|
|
}
|
2016-02-29 22:43:45 +01:00
|
|
|
|
|
|
|
lhs_curr = match op_token {
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::Plus => Expr::FnCall("+".to_string(), vec![lhs_curr, rhs]),
|
|
|
|
Token::Minus => Expr::FnCall("-".to_string(), vec![lhs_curr, rhs]),
|
|
|
|
Token::Multiply => Expr::FnCall("*".to_string(), vec![lhs_curr, rhs]),
|
|
|
|
Token::Divide => Expr::FnCall("/".to_string(), vec![lhs_curr, rhs]),
|
2016-02-29 22:43:45 +01:00
|
|
|
Token::Equals => Expr::Assignment(Box::new(lhs_curr), Box::new(rhs)),
|
2016-03-07 21:39:02 +01:00
|
|
|
Token::Period => Expr::Dot(Box::new(lhs_curr), Box::new(rhs)),
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::EqualTo => Expr::FnCall("==".to_string(), vec![lhs_curr, rhs]),
|
|
|
|
Token::NotEqualTo => Expr::FnCall("!=".to_string(), vec![lhs_curr, rhs]),
|
|
|
|
Token::LessThan => Expr::FnCall("<".to_string(), vec![lhs_curr, rhs]),
|
2016-04-17 04:32:18 +02:00
|
|
|
Token::LessThanEqual => {
|
2017-10-02 23:44:45 +02:00
|
|
|
Expr::FnCall("<=".to_string(), vec![lhs_curr, rhs])
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::GreaterThan => Expr::FnCall(">".to_string(), vec![lhs_curr, rhs]),
|
2016-04-17 04:32:18 +02:00
|
|
|
Token::GreaterThanEqual => {
|
2017-10-02 23:44:45 +02:00
|
|
|
Expr::FnCall(">=".to_string(), vec![lhs_curr, rhs])
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
2017-10-02 23:44:45 +02:00
|
|
|
Token::Or => Expr::FnCall("||".to_string(), vec![lhs_curr, rhs]),
|
|
|
|
Token::And => Expr::FnCall("&&".to_string(), vec![lhs_curr, rhs]),
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => return Err(ParseError::UnknownOperator),
|
2016-02-29 22:43:45 +01:00
|
|
|
};
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_expr<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
|
|
|
|
let lhs = try!(parse_primary(input));
|
|
|
|
|
|
|
|
parse_binop(input, 0, lhs)
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_if<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseError> {
|
|
|
|
input.next();
|
|
|
|
|
|
|
|
let guard = try!(parse_expr(input));
|
|
|
|
let body = try!(parse_block(input));
|
|
|
|
|
2016-03-03 14:20:55 +01:00
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::Else) => {
|
2016-03-03 14:20:55 +01:00
|
|
|
input.next();
|
|
|
|
let else_body = try!(parse_block(input));
|
|
|
|
Ok(Stmt::IfElse(Box::new(guard), Box::new(body), Box::new(else_body)))
|
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => Ok(Stmt::If(Box::new(guard), Box::new(body))),
|
2016-03-03 14:20:55 +01:00
|
|
|
}
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_while<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseError> {
|
|
|
|
input.next();
|
|
|
|
|
|
|
|
let guard = try!(parse_expr(input));
|
|
|
|
let body = try!(parse_block(input));
|
|
|
|
|
|
|
|
Ok(Stmt::While(Box::new(guard), Box::new(body)))
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_var<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseError> {
|
|
|
|
input.next();
|
|
|
|
|
|
|
|
let name = match input.next() {
|
2016-03-02 14:37:28 +01:00
|
|
|
Some(Token::Identifier(ref s)) => s.clone(),
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => return Err(ParseError::VarExpectsIdentifier),
|
2016-02-29 22:43:45 +01:00
|
|
|
};
|
|
|
|
|
|
|
|
match input.peek() {
|
|
|
|
Some(&Token::Equals) => {
|
|
|
|
input.next();
|
|
|
|
let initializer = try!(parse_expr(input));
|
|
|
|
Ok(Stmt::Var(name, Some(Box::new(initializer))))
|
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => Ok(Stmt::Var(name, None)),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_block<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseError> {
|
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::LCurly) => (),
|
|
|
|
_ => return Err(ParseError::MissingLCurly),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
input.next();
|
|
|
|
|
2016-03-01 21:16:10 +01:00
|
|
|
let mut stmts = Vec::new();
|
|
|
|
|
|
|
|
let skip_body = match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::RCurly) => true,
|
|
|
|
_ => false,
|
2016-03-01 21:16:10 +01:00
|
|
|
};
|
|
|
|
|
|
|
|
if !skip_body {
|
|
|
|
while let Some(_) = input.peek() {
|
|
|
|
stmts.push(try!(parse_stmt(input)));
|
|
|
|
|
2017-10-02 23:44:45 +02:00
|
|
|
if let Some(&Token::Semicolon) = input.peek() {
|
|
|
|
input.next();
|
2016-03-01 21:16:10 +01:00
|
|
|
}
|
2017-10-02 23:44:45 +02:00
|
|
|
|
|
|
|
if let Some(&Token::RCurly) = input.peek() { break }
|
2016-04-14 03:01:08 +02:00
|
|
|
}
|
2016-03-01 21:16:10 +01:00
|
|
|
}
|
2016-02-29 22:43:45 +01:00
|
|
|
|
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::RCurly) => {
|
|
|
|
input.next();
|
2017-10-02 23:44:45 +02:00
|
|
|
Ok(Stmt::Block(stmts))
|
2016-04-17 04:32:18 +02:00
|
|
|
}
|
|
|
|
_ => Err(ParseError::MissingRCurly),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_expr_stmt<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseError> {
|
2016-04-14 03:01:08 +02:00
|
|
|
let expr = try!(parse_expr(input));
|
2016-02-29 22:43:45 +01:00
|
|
|
Ok(Stmt::Expr(Box::new(expr)))
|
|
|
|
}
|
|
|
|
|
|
|
|
fn parse_stmt<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseError> {
|
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::If) => parse_if(input),
|
|
|
|
Some(&Token::While) => parse_while(input),
|
|
|
|
Some(&Token::Break) => {
|
|
|
|
input.next();
|
|
|
|
Ok(Stmt::Break)
|
|
|
|
}
|
|
|
|
Some(&Token::Return) => {
|
2016-04-14 03:01:08 +02:00
|
|
|
input.next();
|
2016-03-03 15:31:42 +01:00
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::Semicolon) => Ok(Stmt::Return),
|
|
|
|
_ => {
|
|
|
|
let ret = try!(parse_expr(input));
|
|
|
|
Ok(Stmt::ReturnWithVal(Box::new(ret)))
|
|
|
|
}
|
2016-03-03 15:31:42 +01:00
|
|
|
}
|
|
|
|
}
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::LCurly) => parse_block(input),
|
|
|
|
Some(&Token::Var) => parse_var(input),
|
|
|
|
_ => parse_expr_stmt(input),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2016-03-01 21:16:10 +01:00
|
|
|
fn parse_fn<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<FnDef, ParseError> {
|
|
|
|
input.next();
|
2016-02-29 22:43:45 +01:00
|
|
|
|
2016-03-01 21:16:10 +01:00
|
|
|
let name = match input.next() {
|
2016-03-02 14:37:28 +01:00
|
|
|
Some(Token::Identifier(ref s)) => s.clone(),
|
2016-04-17 04:32:18 +02:00
|
|
|
_ => return Err(ParseError::FnMissingName),
|
2016-03-01 21:16:10 +01:00
|
|
|
};
|
|
|
|
|
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::LParen) => {
|
|
|
|
input.next();
|
|
|
|
}
|
|
|
|
_ => return Err(ParseError::FnMissingParams),
|
2016-03-01 21:16:10 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
let mut params = Vec::new();
|
|
|
|
|
|
|
|
let skip_params = match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::RParen) => {
|
|
|
|
input.next();
|
|
|
|
true
|
|
|
|
}
|
|
|
|
_ => false,
|
2016-03-01 21:16:10 +01:00
|
|
|
};
|
|
|
|
|
|
|
|
if !skip_params {
|
|
|
|
loop {
|
|
|
|
match input.next() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(Token::RParen) => break,
|
2016-03-01 21:16:10 +01:00
|
|
|
Some(Token::Comma) => (),
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(Token::Identifier(ref s)) => {
|
|
|
|
params.push(s.clone());
|
|
|
|
}
|
|
|
|
_ => return Err(ParseError::MalformedCallExpr),
|
2016-03-01 21:16:10 +01:00
|
|
|
}
|
2016-04-14 03:01:08 +02:00
|
|
|
}
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
2016-03-01 21:16:10 +01:00
|
|
|
let body = try!(parse_block(input));
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
Ok(FnDef {
|
|
|
|
name: name,
|
|
|
|
params: params,
|
|
|
|
body: Box::new(body),
|
|
|
|
})
|
2016-03-01 21:16:10 +01:00
|
|
|
}
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
fn parse_top_level<'a>(input: &mut Peekable<TokenIterator<'a>>)
|
|
|
|
-> Result<(Vec<Stmt>, Vec<FnDef>), ParseError> {
|
2016-03-01 21:16:10 +01:00
|
|
|
let mut stmts = Vec::new();
|
|
|
|
let mut fndefs = Vec::new();
|
|
|
|
|
2016-02-29 22:43:45 +01:00
|
|
|
while let Some(_) = input.peek() {
|
|
|
|
match input.peek() {
|
2016-04-17 04:32:18 +02:00
|
|
|
Some(&Token::Fn) => fndefs.push(try!(parse_fn(input))),
|
|
|
|
_ => stmts.push(try!(parse_stmt(input))),
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
2017-10-02 23:44:45 +02:00
|
|
|
if let Some(&Token::Semicolon) = input.peek() {
|
|
|
|
input.next();
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2016-03-01 21:16:10 +01:00
|
|
|
Ok((stmts, fndefs))
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|
|
|
|
|
2016-04-17 04:32:18 +02:00
|
|
|
pub fn parse<'a>(input: &mut Peekable<TokenIterator<'a>>)
|
|
|
|
-> Result<(Vec<Stmt>, Vec<FnDef>), ParseError> {
|
2016-03-01 21:16:10 +01:00
|
|
|
parse_top_level(input)
|
2016-02-29 22:43:45 +01:00
|
|
|
}
|