Fully fixed binop parsing
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19a344fa77
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@ -201,29 +201,36 @@ fn while_expression(tokens: &mut Tokens) -> ParseResult {
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fn binop_expression(precedence: i32, tokens: &mut Tokens) -> ParseResult {
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fn binop_expression(precedence: i32, tokens: &mut Tokens) -> ParseResult {
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//TODO left needs to match on an identifiers vs. a prefix operator and return *that* AST
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//TODO left needs to match on an identifiers vs. a prefix operator and return *that* AST
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let left: AST = match simple_expression(tokens) {
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let mut left: AST = match simple_expression(tokens) {
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err@ParseResult::Err(_) => return err,
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err@ParseResult::Err(_) => return err,
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ParseResult::Ok(ast) => ast
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ParseResult::Ok(ast) => ast
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};
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};
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loop {
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let lookahead: Option<&Token> = tokens.peek().map(|i| i.clone());
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let lookahead: Option<&Token> = tokens.peek().map(|i| i.clone());
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let precedence = lookahead.and_then(|t| get_binop_precedence(t));
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let next_precedence = lookahead.and_then(|t| get_binop_precedence(t));
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if let None = precedence {
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match next_precedence {
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return ParseResult::Ok(left);
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Some(next) if precedence < next => {
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left = match binop_rhs(next, left, tokens) {
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err@ParseResult::Err(_) => return err,
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ParseResult::Ok(ast) => ast
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};
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},
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_ => return ParseResult::Ok(left),
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}
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}
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}
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}
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binop_rhs(left, tokens)
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fn binop_rhs(precedence: i32, lhs: AST, tokens: &mut Tokens) -> ParseResult {
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}
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fn binop_rhs(lhs: AST, tokens: &mut Tokens) -> ParseResult {
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let op: AST = match simple_expression(tokens) {
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let op: AST = match simple_expression(tokens) {
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err@ParseResult::Err(_) => return err,
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err@ParseResult::Err(_) => return err,
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ParseResult::Ok(ast) => ast
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ParseResult::Ok(ast) => ast
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};
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};
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let rhs: AST = match binop_expression(0, tokens) {
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let rhs: AST = match binop_expression(precedence, tokens) {
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err@ParseResult::Err(_) => return err,
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err@ParseResult::Err(_) => return err,
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ParseResult::Ok(ast) => ast
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ParseResult::Ok(ast) => ast
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};
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};
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@ -244,8 +251,8 @@ fn get_binop_precedence(token: &Token) -> Option<i32> {
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match &identifier_str[..] {
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match &identifier_str[..] {
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"+" => Some(20),
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"+" => Some(20),
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"-" => Some(20),
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"-" => Some(20),
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"*" => Some(20),
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"*" => Some(40),
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"/" => Some(20),
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"/" => Some(40),
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_ => None
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_ => None
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}
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}
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}
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}
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