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Parsing for if-statements, following #285.

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This commit is contained in:
Richard Smith
2021-04-19 17:09:54 -07:00
parent 8280be1c36
commit 5d6947186d
4 changed files with 201 additions and 1 deletions
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parser/parser_impl.cpp
+64 -1
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@@ -9,6 +9,7 @@
#include "lexer/token_kind.h"
#include "lexer/tokenized_buffer.h"
#include "llvm/ADT/Optional.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/raw_ostream.h"
#include "parser/parse_node_kind.h"
#include "parser/parse_tree.h"
@@ -65,10 +66,24 @@ struct ExpectedExpression : SimpleDiagnostic<ExpectedExpression> {
static constexpr llvm::StringLiteral Message = "Expected expression.";
};
struct ExpectedParenAfter : SimpleDiagnostic<ExpectedParenAfter> {
static constexpr llvm::StringLiteral ShortName = "syntax-error";
static constexpr const char* Message = "Expected `(` after `{0}`.";
TokenKind introducer;
auto Format() -> std::string {
return llvm::formatv(Message, introducer.GetFixedSpelling()).str();
}
};
struct ExpectedCloseParen : SimpleDiagnostic<ExpectedCloseParen> {
static constexpr llvm::StringLiteral ShortName = "syntax-error";
static constexpr llvm::StringLiteral Message =
"Unexpected tokens before `)`.";
// TODO: Include the location of the matching open paren in the diagnostic.
TokenizedBuffer::Token open_paren;
};
struct ExpectedSemiAfterExpression
@@ -495,7 +510,8 @@ auto ParseTree::Parser::ParseParenExpression() -> llvm::Optional<Node> {
if (tokens.GetKind(*position) != TokenKind::CloseParen()) {
if (!has_errors) {
emitter.EmitError<ExpectedCloseParen>(*position);
emitter.EmitError<ExpectedCloseParen>(*position,
{.open_paren = open_paren});
has_errors = true;
}
SkipTo(tokens.GetMatchedClosingToken(open_paren));
@@ -712,11 +728,58 @@ auto ParseTree::Parser::ParseExpressionStatement() -> llvm::Optional<Node> {
return llvm::None;
}
auto ParseTree::Parser::ParseParenCondition(TokenKind introducer)
-> llvm::Optional<Node> {
// `(` expression `)`
auto start = StartSubtree();
auto open_paren = ConsumeIf(TokenKind::OpenParen());
if (!open_paren) {
emitter.EmitError<ExpectedParenAfter>(*position,
{.introducer = introducer});
}
auto expr = ParseExpression();
if (!open_paren) {
// Don't expect a matching closing paren if there wasn't an opening paren.
return llvm::None;
}
bool has_errors = false;
if (tokens.GetKind(*position) != TokenKind::CloseParen()) {
emitter.EmitError<ExpectedCloseParen>(*position,
{.open_paren = *open_paren});
SkipTo(tokens.GetMatchedClosingToken(*open_paren));
has_errors = true;
}
AddLeafNode(ParseNodeKind::ConditionEnd(), Consume(TokenKind::CloseParen()));
return AddNode(ParseNodeKind::Condition(), *open_paren, start,
/*has_errors=*/!expr || has_errors);
}
auto ParseTree::Parser::ParseIfStatement() -> llvm::Optional<Node> {
auto start = StartSubtree();
auto if_token = Consume(TokenKind::IfKeyword());
auto cond = ParseParenCondition(TokenKind::IfKeyword());
auto then_case = ParseStatement();
bool else_has_errors = false;
if (ConsumeAndAddLeafNodeIf(TokenKind::ElseKeyword(),
ParseNodeKind::IfStatementElse())) {
else_has_errors = !ParseStatement();
}
return AddNode(ParseNodeKind::IfStatement(), if_token, start,
/*has_errors=*/!cond || !then_case || else_has_errors);
}
auto ParseTree::Parser::ParseStatement() -> llvm::Optional<Node> {
switch (tokens.GetKind(*position)) {
case TokenKind::VarKeyword():
return ParseVariableDeclaration();
case TokenKind::IfKeyword():
return ParseIfStatement();
case TokenKind::OpenCurlyBrace():
return ParseCodeBlock();