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Starting on guards

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greg 2018-07-13 20:18:57 -07:00
parent 21a8868bcf
commit 8aa33d0872
1 changed files with 12 additions and 4 deletions
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16
schala-lang/src/parsing.rs
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@ -120,9 +120,12 @@ tuple_struct_pattern := IDENTIFIER '(' (pattern, ',')* ')'
/* Expression - If */ /* Expression - If */
if_expr := 'if' discriminator ('then' condititional | 'is' simple_pattern_match | guard_block) if_expr := 'if' discriminator ('then' condititional | 'is' simple_pattern_match | guard_block)
discriminator := modified_precedence_expression discriminator := modified_precedence_expression
modified_precedence_expression := ???
conditional := block else_clause conditional := block else_clause
simple_pattern_match := pattern 'then' conditional simple_pattern_match := pattern 'then' conditional
else_clause := ε | 'else' block else_clause := ε | 'else' block
guard_block := '{' (guard, ',')* '}'
guard := ??
/* Expression - While */ /* Expression - While */
while_expr := 'while' while_cond '{' (statement delimiter)* '}' while_expr := 'while' while_cond '{' (statement delimiter)* '}'
@ -688,10 +691,6 @@ impl Parser {
Ok(IfExpressionBody::SimplePatternMatch(pat, then_clause, else_clause)) Ok(IfExpressionBody::SimplePatternMatch(pat, then_clause, else_clause))
}); });
parse_method!(guard_block(&mut self) -> ParseResult<IfExpressionBody> {
ParseError::new("Rest of if not done")
});
parse_method!(else_clause(&mut self) -> ParseResult<Option<Block>> { parse_method!(else_clause(&mut self) -> ParseResult<Option<Block>> {
Ok(if let Keyword(Kw::Else) = self.peek() { Ok(if let Keyword(Kw::Else) = self.peek() {
self.next(); self.next();
@ -701,6 +700,15 @@ impl Parser {
}) })
}); });
parse_method!(guard_block(&mut self) -> ParseResult<IfExpressionBody> {
let guards = delimited!(self, LCurlyBrace, guard, Comma, RCurlyBrace);
Ok(IfExpressionBody::GuardList(guards))
});
parse_method!(guard(&mut self) -> ParseResult<Guard> {
unimplemented!()
});
parse_method!(pattern(&mut self) -> ParseResult<Pattern> { parse_method!(pattern(&mut self) -> ParseResult<Pattern> {
if let LParen = self.peek() { if let LParen = self.peek() {
let tuple_pattern_variants = delimited!(self, LParen, pattern, Comma, RParen); let tuple_pattern_variants = delimited!(self, LParen, pattern, Comma, RParen);