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[toolchain] Parse variables and parameters as 'name: Type'. (#574)

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Factor out code for pattern parsing, that only recognizes this form for
now, and uniformly form a 'PatternBinding' parse node for this, for
both variables and patterns.
This commit is contained in:
Richard Smith
2021-06-14 14:28:45 -07:00
committed by GitHub
parent 47ee66feef
commit 61b30b1243
6 changed files with 103 additions and 58 deletions
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toolchain/parser/parser_impl.cpp
+39 -27
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@@ -45,13 +45,13 @@ struct ExpectedFunctionBodyOrSemi
struct ExpectedVariableName : SimpleDiagnostic<ExpectedVariableName> {
static constexpr llvm::StringLiteral ShortName = "syntax-error";
static constexpr llvm::StringLiteral Message =
"Expected variable name after type in `var` declaration.";
"Expected pattern in `var` declaration.";
};
struct ExpectedParameterName : SimpleDiagnostic<ExpectedParameterName> {
static constexpr llvm::StringLiteral ShortName = "syntax-error";
static constexpr llvm::StringLiteral Message =
"Expected parameter name after type in parameter declaration.";
"Expected parameter declaration.";
};
struct UnrecognizedDeclaration : SimpleDiagnostic<UnrecognizedDeclaration> {
@@ -376,23 +376,34 @@ auto ParseTree::Parser::ParseParenList(ListElementParser list_element_parser,
return list_handler(open_paren, Consume(TokenKind::CloseParen()), has_errors);
}
auto ParseTree::Parser::ParseFunctionParameter() -> llvm::Optional<Node> {
// A parameter is of the form
// type identifier
auto start = GetSubtreeStartPosition();
auto type = ParseType();
// FIXME: We can't use DeclaredName here because we need to use the
// identifier token as the root token in the parameter node.
auto name = ConsumeIf(TokenKind::Identifier());
if (!name) {
emitter.EmitError<ExpectedParameterName>(*position);
return llvm::None;
auto ParseTree::Parser::ParsePattern(PatternKind kind) -> llvm::Optional<Node> {
if (NextTokenIs(TokenKind::Identifier()) &&
tokens.GetKind(*(position + 1)) == TokenKind::Colon()) {
// identifier `:` type
auto start = GetSubtreeStartPosition();
AddLeafNode(ParseNodeKind::DeclaredName(),
Consume(TokenKind::Identifier()));
auto colon = Consume(TokenKind::Colon());
auto type = ParseType();
return AddNode(ParseNodeKind::PatternBinding(), colon, start,
/*has_error=*/!type);
}
return AddNode(ParseNodeKind::ParameterDeclaration(), *name, start,
/*has_error=*/!type);
switch (kind) {
case PatternKind::Parameter:
emitter.EmitError<ExpectedParameterName>(*position);
break;
case PatternKind::Variable:
emitter.EmitError<ExpectedVariableName>(*position);
break;
}
return llvm::None;
}
auto ParseTree::Parser::ParseFunctionParameter() -> llvm::Optional<Node> {
return ParsePattern(PatternKind::Parameter);
}
auto ParseTree::Parser::ParseFunctionSignature() -> bool {
@@ -507,18 +518,15 @@ auto ParseTree::Parser::ParseFunctionDeclaration() -> Node {
}
auto ParseTree::Parser::ParseVariableDeclaration() -> Node {
// `var` expression identifier [= expression] `;`
// `var` pattern [= expression] `;`
TokenizedBuffer::Token var_token = Consume(TokenKind::VarKeyword());
auto start = GetSubtreeStartPosition();
auto type = ParseType();
auto name = ConsumeAndAddLeafNodeIf(TokenKind::Identifier(),
ParseNodeKind::DeclaredName());
if (!name) {
emitter.EmitError<ExpectedVariableName>(*position);
if (auto after_name = FindNextOf({TokenKind::Equal(), TokenKind::Semi()})) {
SkipTo(*after_name);
auto pattern = ParsePattern(PatternKind::Variable);
if (!pattern) {
if (auto after_pattern =
FindNextOf({TokenKind::Equal(), TokenKind::Semi()})) {
SkipTo(*after_pattern);
}
}
@@ -538,7 +546,7 @@ auto ParseTree::Parser::ParseVariableDeclaration() -> Node {
}
return AddNode(ParseNodeKind::VariableDeclaration(), var_token, start,
/*has_error=*/!type || !name || !semi);
/*has_error=*/!pattern || !semi);
}
auto ParseTree::Parser::ParseEmptyDeclaration() -> Node {
@@ -744,6 +752,10 @@ auto ParseTree::Parser::ParseExpression() -> llvm::Optional<Node> {
return ParseOperatorExpression(PrecedenceGroup::ForTopLevelExpression());
}
auto ParseTree::Parser::ParseType() -> llvm::Optional<Node> {
return ParseOperatorExpression(PrecedenceGroup::ForType());
}
auto ParseTree::Parser::ParseExpressionStatement() -> llvm::Optional<Node> {
TokenizedBuffer::Token start_token = *position;
auto start = GetSubtreeStartPosition();