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parser: improve readability i guess

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anna 2021-04-15 01:51:58 +02:00
parent 1f86885424
commit 83441a7b57
Signed by: fef
GPG key ID: EC22E476DC2D3D84
1 changed files with 18 additions and 21 deletions
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39
src/parser.rs
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@ -15,23 +15,23 @@ impl <'a> Parser<'a> {
} }
} }
fn parse_node(&mut self, first: Token) -> Result<Node, SyntaxError> { fn parse_node(&mut self) -> Option<Result<Node, SyntaxError>> {
match first.kind { Some(self.lexer.next()?.and_then(|token| match token.kind {
TokenKind::Ident(name) => self.require_kind( TokenKind::Ident(name) => {
TokenKind::Eq self.require_kind(TokenKind::Eq ).and_then(|_| {
).and_then(|_| { self.require_next()
self.require_next() }).and_then(|token| match token.kind {
}).and_then(|token| match token.kind { TokenKind::TrueKeyword => self.node_result(name, NodeVal::Bool(true)),
TokenKind::TrueKeyword => self.make_node_result(name, NodeVal::Bool(true)), TokenKind::FalseKeyword => self.node_result(name, NodeVal::Bool(false)),
TokenKind::FalseKeyword => self.make_node_result(name, NodeVal::Bool(false)), TokenKind::IntLiteral(i) => self.node_result(name, NodeVal::Int(i)),
TokenKind::IntLiteral(i) => self.make_node_result(name, NodeVal::Int(i)), TokenKind::StringLiteral(s) => self.node_result(name, NodeVal::String(s)),
TokenKind::StringLiteral(s) => self.make_node_result(name, NodeVal::String(String::from(s))), _ => self.lexer.syntax_error(String::from("Expected a value")),
_ => self.lexer.syntax_error(String::from("Expected a value")), }).and_then(|node| {
}).and_then(|node| { self.require_kind(TokenKind::Semi).and_then(|_| Ok(node))
self.require_kind(TokenKind::Semi).and_then(|_| Ok(node)) })
}), },
_ => self.lexer.syntax_error(String::from("Expected identifier")), _ => self.lexer.syntax_error(String::from("Expected identifier")),
} }))
} }
fn require_kind(&mut self, kind: TokenKind) -> Result<Token, SyntaxError> { fn require_kind(&mut self, kind: TokenKind) -> Result<Token, SyntaxError> {
@ -51,7 +51,7 @@ impl <'a> Parser<'a> {
} }
} }
fn make_node_result<T>(&self, name: String, val: NodeVal) -> Result<Node, T> { fn node_result<T>(&self, name: String, val: NodeVal) -> Result<Node, T> {
Ok(self.make_node(name, val)) Ok(self.make_node(name, val))
} }
@ -67,10 +67,7 @@ impl <'a> Iterator for Parser<'a> {
type Item = Result<Node, SyntaxError>; type Item = Result<Node, SyntaxError>;
fn next(&mut self) -> Option<Result<Node, SyntaxError>> { fn next(&mut self) -> Option<Result<Node, SyntaxError>> {
Some(match self.lexer.next()? { self.parse_node()
Ok(t) => self.parse_node(t),
Err(e) => Err(e),
})
} }
} }