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llvm-project/clang/lib/ASTMatchers/Dynamic/Parser.cpp

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//===- Parser.cpp - Matcher expression parser -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Recursive parser implementation for the matcher expression grammar.
///
//===----------------------------------------------------------------------===//
#include "clang/ASTMatchers/Dynamic/Parser.h"
#include "clang/ASTMatchers/ASTMatchersInternal.h"
#include "clang/ASTMatchers/Dynamic/Diagnostics.h"
#include "clang/ASTMatchers/Dynamic/Registry.h"
#include "clang/Basic/CharInfo.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ManagedStatic.h"
#include <algorithm>
#include <cassert>
#include <cerrno>
#include <cstddef>
#include <cstdlib>
#include <string>
#include <utility>
#include <vector>
namespace clang {
namespace ast_matchers {
namespace dynamic {
/// Simple structure to hold information for one token from the parser.
struct Parser::TokenInfo {
/// Different possible tokens.
enum TokenKind {
TK_Eof,
TK_OpenParen,
TK_CloseParen,
TK_Comma,
TK_Period,
TK_Literal,
TK_Ident,
TK_InvalidChar,
TK_Error,
TK_CodeCompletion
};
/// Some known identifiers.
static const char* const ID_Bind;
TokenInfo() = default;
StringRef Text;
TokenKind Kind = TK_Eof;
SourceRange Range;
VariantValue Value;
};
const char* const Parser::TokenInfo::ID_Bind = "bind";
/// Simple tokenizer for the parser.
class Parser::CodeTokenizer {
public:
explicit CodeTokenizer(StringRef MatcherCode, Diagnostics *Error)
: Code(MatcherCode), StartOfLine(MatcherCode), Error(Error) {
NextToken = getNextToken();
}
CodeTokenizer(StringRef MatcherCode, Diagnostics *Error,
unsigned CodeCompletionOffset)
: Code(MatcherCode), StartOfLine(MatcherCode), Error(Error),
CodeCompletionLocation(MatcherCode.data() + CodeCompletionOffset) {
NextToken = getNextToken();
}
/// Returns but doesn't consume the next token.
const TokenInfo &peekNextToken() const { return NextToken; }
/// Consumes and returns the next token.
TokenInfo consumeNextToken() {
TokenInfo ThisToken = NextToken;
NextToken = getNextToken();
return ThisToken;
}
TokenInfo::TokenKind nextTokenKind() const { return NextToken.Kind; }
private:
TokenInfo getNextToken() {
consumeWhitespace();
TokenInfo Result;
Result.Range.Start = currentLocation();
if (CodeCompletionLocation && CodeCompletionLocation <= Code.data()) {
Result.Kind = TokenInfo::TK_CodeCompletion;
Result.Text = StringRef(CodeCompletionLocation, 0);
CodeCompletionLocation = nullptr;
return Result;
}
if (Code.empty()) {
Result.Kind = TokenInfo::TK_Eof;
Result.Text = "";
return Result;
}
switch (Code[0]) {
case '#':
Result.Kind = TokenInfo::TK_Eof;
Result.Text = "";
return Result;
case ',':
Result.Kind = TokenInfo::TK_Comma;
Result.Text = Code.substr(0, 1);
Code = Code.drop_front();
break;
case '.':
Result.Kind = TokenInfo::TK_Period;
Result.Text = Code.substr(0, 1);
Code = Code.drop_front();
break;
case '(':
Result.Kind = TokenInfo::TK_OpenParen;
Result.Text = Code.substr(0, 1);
Code = Code.drop_front();
break;
case ')':
Result.Kind = TokenInfo::TK_CloseParen;
Result.Text = Code.substr(0, 1);
Code = Code.drop_front();
break;
case '"':
case '\'':
// Parse a string literal.
consumeStringLiteral(&Result);
break;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
// Parse an unsigned and float literal.
consumeNumberLiteral(&Result);
break;
default:
if (isAlphanumeric(Code[0])) {
// Parse an identifier
size_t TokenLength = 1;
while (true) {
// A code completion location in/immediately after an identifier will
// cause the portion of the identifier before the code completion
// location to become a code completion token.
if (CodeCompletionLocation == Code.data() + TokenLength) {
CodeCompletionLocation = nullptr;
Result.Kind = TokenInfo::TK_CodeCompletion;
Result.Text = Code.substr(0, TokenLength);
Code = Code.drop_front(TokenLength);
return Result;
}
if (TokenLength == Code.size() || !isAlphanumeric(Code[TokenLength]))
break;
++TokenLength;
}
if (TokenLength == 4 && Code.startswith("true")) {
Result.Kind = TokenInfo::TK_Literal;
Result.Value = true;
} else if (TokenLength == 5 && Code.startswith("false")) {
Result.Kind = TokenInfo::TK_Literal;
Result.Value = false;
} else {
Result.Kind = TokenInfo::TK_Ident;
Result.Text = Code.substr(0, TokenLength);
}
Code = Code.drop_front(TokenLength);
} else {
Result.Kind = TokenInfo::TK_InvalidChar;
Result.Text = Code.substr(0, 1);
Code = Code.drop_front(1);
}
break;
}
Result.Range.End = currentLocation();
return Result;
}
/// Consume an unsigned and float literal.
void consumeNumberLiteral(TokenInfo *Result) {
bool isFloatingLiteral = false;
unsigned Length = 1;
if (Code.size() > 1) {
// Consume the 'x' or 'b' radix modifier, if present.
switch (toLowercase(Code[1])) {
case 'x': case 'b': Length = 2;
}
}
while (Length < Code.size() && isHexDigit(Code[Length]))
++Length;
// Try to recognize a floating point literal.
while (Length < Code.size()) {
char c = Code[Length];
if (c == '-' || c == '+' || c == '.' || isHexDigit(c)) {
isFloatingLiteral = true;
Length++;
} else {
break;
}
}
Result->Text = Code.substr(0, Length);
Code = Code.drop_front(Length);
if (isFloatingLiteral) {
char *end;
errno = 0;
std::string Text = Result->Text.str();
double doubleValue = strtod(Text.c_str(), &end);
if (*end == 0 && errno == 0) {
Result->Kind = TokenInfo::TK_Literal;
Result->Value = doubleValue;
return;
}
} else {
unsigned Value;
if (!Result->Text.getAsInteger(0, Value)) {
Result->Kind = TokenInfo::TK_Literal;
Result->Value = Value;
return;
}
}
SourceRange Range;
Range.Start = Result->Range.Start;
Range.End = currentLocation();
Error->addError(Range, Error->ET_ParserNumberError) << Result->Text;
Result->Kind = TokenInfo::TK_Error;
}
/// Consume a string literal.
///
/// \c Code must be positioned at the start of the literal (the opening
/// quote). Consumed until it finds the same closing quote character.
void consumeStringLiteral(TokenInfo *Result) {
bool InEscape = false;
const char Marker = Code[0];
for (size_t Length = 1, Size = Code.size(); Length != Size; ++Length) {
if (InEscape) {
InEscape = false;
continue;
}
if (Code[Length] == '\\') {
InEscape = true;
continue;
}
if (Code[Length] == Marker) {
Result->Kind = TokenInfo::TK_Literal;
Result->Text = Code.substr(0, Length + 1);
Result->Value = Code.substr(1, Length - 1);
Code = Code.drop_front(Length + 1);
return;
}
}
StringRef ErrorText = Code;
Code = Code.drop_front(Code.size());
SourceRange Range;
Range.Start = Result->Range.Start;
Range.End = currentLocation();
Error->addError(Range, Error->ET_ParserStringError) << ErrorText;
Result->Kind = TokenInfo::TK_Error;
}
/// Consume all leading whitespace from \c Code.
void consumeWhitespace() {
while (!Code.empty() && isWhitespace(Code[0])) {
if (Code[0] == '\n') {
++Line;
StartOfLine = Code.drop_front();
}
Code = Code.drop_front();
}
}
SourceLocation currentLocation() {
SourceLocation Location;
Location.Line = Line;
Location.Column = Code.data() - StartOfLine.data() + 1;
return Location;
}
StringRef Code;
StringRef StartOfLine;
unsigned Line = 1;
Diagnostics *Error;
TokenInfo NextToken;
const char *CodeCompletionLocation = nullptr;
};
Parser::Sema::~Sema() = default;
std::vector<ArgKind> Parser::Sema::getAcceptedCompletionTypes(
llvm::ArrayRef<std::pair<MatcherCtor, unsigned>> Context) {
return {};
}
std::vector<MatcherCompletion>
Parser::Sema::getMatcherCompletions(llvm::ArrayRef<ArgKind> AcceptedTypes) {
return {};
}
struct Parser::ScopedContextEntry {
Parser *P;
ScopedContextEntry(Parser *P, MatcherCtor C) : P(P) {
P->ContextStack.push_back(std::make_pair(C, 0u));
}
~ScopedContextEntry() {
P->ContextStack.pop_back();
}
void nextArg() {
++P->ContextStack.back().second;
}
};
/// Parse expressions that start with an identifier.
///
/// This function can parse named values and matchers.
/// In case of failure it will try to determine the user's intent to give
/// an appropriate error message.
bool Parser::parseIdentifierPrefixImpl(VariantValue *Value) {
const TokenInfo NameToken = Tokenizer->consumeNextToken();
if (Tokenizer->nextTokenKind() != TokenInfo::TK_OpenParen) {
// Parse as a named value.
if (const VariantValue NamedValue =
NamedValues ? NamedValues->lookup(NameToken.Text)
: VariantValue()) {
if (Tokenizer->nextTokenKind() != TokenInfo::TK_Period) {
*Value = NamedValue;
return true;
}
std::string BindID;
if (!parseBindID(BindID))
return false;
assert(NamedValue.isMatcher());
llvm::Optional<DynTypedMatcher> Result =
NamedValue.getMatcher().getSingleMatcher();
if (Result.hasValue()) {
llvm::Optional<DynTypedMatcher> Bound = Result->tryBind(BindID);
if (Bound.hasValue()) {
*Value = VariantMatcher::SingleMatcher(*Bound);
return true;
}
}
return false;
}
// If the syntax is correct and the name is not a matcher either, report
// unknown named value.
if ((Tokenizer->nextTokenKind() == TokenInfo::TK_Comma ||
Tokenizer->nextTokenKind() == TokenInfo::TK_CloseParen ||
Tokenizer->nextTokenKind() == TokenInfo::TK_Eof) &&
!S->lookupMatcherCtor(NameToken.Text)) {
Error->addError(NameToken.Range, Error->ET_RegistryValueNotFound)
<< NameToken.Text;
return false;
}
// Otherwise, fallback to the matcher parser.
}
// Parse as a matcher expression.
return parseMatcherExpressionImpl(NameToken, Value);
}
bool Parser::parseBindID(std::string &BindID) {
// Parse .bind("foo")
assert(Tokenizer->peekNextToken().Kind == TokenInfo::TK_Period);
Tokenizer->consumeNextToken(); // consume the period.
const TokenInfo BindToken = Tokenizer->consumeNextToken();
if (BindToken.Kind == TokenInfo::TK_CodeCompletion) {
addCompletion(BindToken, MatcherCompletion("bind(\"", "bind", 1));
return false;
}
const TokenInfo OpenToken = Tokenizer->consumeNextToken();
const TokenInfo IDToken = Tokenizer->consumeNextToken();
const TokenInfo CloseToken = Tokenizer->consumeNextToken();
// TODO: We could use different error codes for each/some to be more
// explicit about the syntax error.
if (BindToken.Kind != TokenInfo::TK_Ident ||
BindToken.Text != TokenInfo::ID_Bind) {
Error->addError(BindToken.Range, Error->ET_ParserMalformedBindExpr);
return false;
}
if (OpenToken.Kind != TokenInfo::TK_OpenParen) {
Error->addError(OpenToken.Range, Error->ET_ParserMalformedBindExpr);
return false;
}
if (IDToken.Kind != TokenInfo::TK_Literal || !IDToken.Value.isString()) {
Error->addError(IDToken.Range, Error->ET_ParserMalformedBindExpr);
return false;
}
if (CloseToken.Kind != TokenInfo::TK_CloseParen) {
Error->addError(CloseToken.Range, Error->ET_ParserMalformedBindExpr);
return false;
}
BindID = IDToken.Value.getString();
return true;
}
/// Parse and validate a matcher expression.
/// \return \c true on success, in which case \c Value has the matcher parsed.
/// If the input is malformed, or some argument has an error, it
/// returns \c false.
bool Parser::parseMatcherExpressionImpl(const TokenInfo &NameToken,
VariantValue *Value) {
assert(NameToken.Kind == TokenInfo::TK_Ident);
const TokenInfo OpenToken = Tokenizer->consumeNextToken();
if (OpenToken.Kind != TokenInfo::TK_OpenParen) {
Error->addError(OpenToken.Range, Error->ET_ParserNoOpenParen)
<< OpenToken.Text;
return false;
}
llvm::Optional<MatcherCtor> Ctor = S->lookupMatcherCtor(NameToken.Text);
if (!Ctor) {
Error->addError(NameToken.Range, Error->ET_RegistryMatcherNotFound)
<< NameToken.Text;
// Do not return here. We need to continue to give completion suggestions.
}
std::vector<ParserValue> Args;
TokenInfo EndToken;
{
ScopedContextEntry SCE(this, Ctor ? *Ctor : nullptr);
while (Tokenizer->nextTokenKind() != TokenInfo::TK_Eof) {
if (Tokenizer->nextTokenKind() == TokenInfo::TK_CloseParen) {
// End of args.
EndToken = Tokenizer->consumeNextToken();
break;
}
if (!Args.empty()) {
// We must find a , token to continue.
const TokenInfo CommaToken = Tokenizer->consumeNextToken();
if (CommaToken.Kind != TokenInfo::TK_Comma) {
Error->addError(CommaToken.Range, Error->ET_ParserNoComma)
<< CommaToken.Text;
return false;
}
}
Diagnostics::Context Ctx(Diagnostics::Context::MatcherArg, Error,
NameToken.Text, NameToken.Range,
Args.size() + 1);
ParserValue ArgValue;
ArgValue.Text = Tokenizer->peekNextToken().Text;
ArgValue.Range = Tokenizer->peekNextToken().Range;
if (!parseExpressionImpl(&ArgValue.Value)) {
return false;
}
Args.push_back(ArgValue);
SCE.nextArg();
}
}
if (EndToken.Kind == TokenInfo::TK_Eof) {
Error->addError(OpenToken.Range, Error->ET_ParserNoCloseParen);
return false;
}
std::string BindID;
if (Tokenizer->peekNextToken().Kind == TokenInfo::TK_Period) {
if (!parseBindID(BindID))
return false;
}
if (!Ctor)
return false;
// Merge the start and end infos.
Diagnostics::Context Ctx(Diagnostics::Context::ConstructMatcher, Error,
NameToken.Text, NameToken.Range);
SourceRange MatcherRange = NameToken.Range;
MatcherRange.End = EndToken.Range.End;
VariantMatcher Result = S->actOnMatcherExpression(
*Ctor, MatcherRange, BindID, Args, Error);
if (Result.isNull()) return false;
*Value = Result;
return true;
}
// If the prefix of this completion matches the completion token, add it to
// Completions minus the prefix.
void Parser::addCompletion(const TokenInfo &CompToken,
const MatcherCompletion& Completion) {
if (StringRef(Completion.TypedText).startswith(CompToken.Text) &&
Completion.Specificity > 0) {
Completions.emplace_back(Completion.TypedText.substr(CompToken.Text.size()),
Completion.MatcherDecl, Completion.Specificity);
}
}
std::vector<MatcherCompletion> Parser::getNamedValueCompletions(
ArrayRef<ArgKind> AcceptedTypes) {
if (!NamedValues) return std::vector<MatcherCompletion>();
std::vector<MatcherCompletion> Result;
for (const auto &Entry : *NamedValues) {
unsigned Specificity;
if (Entry.getValue().isConvertibleTo(AcceptedTypes, &Specificity)) {
std::string Decl =
(Entry.getValue().getTypeAsString() + " " + Entry.getKey()).str();
Result.emplace_back(Entry.getKey(), Decl, Specificity);
}
}
return Result;
}
void Parser::addExpressionCompletions() {
const TokenInfo CompToken = Tokenizer->consumeNextToken();
assert(CompToken.Kind == TokenInfo::TK_CodeCompletion);
// We cannot complete code if there is an invalid element on the context
// stack.
for (ContextStackTy::iterator I = ContextStack.begin(),
E = ContextStack.end();
I != E; ++I) {
if (!I->first)
return;
}
auto AcceptedTypes = S->getAcceptedCompletionTypes(ContextStack);
for (const auto &Completion : S->getMatcherCompletions(AcceptedTypes)) {
addCompletion(CompToken, Completion);
}
for (const auto &Completion : getNamedValueCompletions(AcceptedTypes)) {
addCompletion(CompToken, Completion);
}
}
/// Parse an <Expression>
bool Parser::parseExpressionImpl(VariantValue *Value) {
switch (Tokenizer->nextTokenKind()) {
case TokenInfo::TK_Literal:
*Value = Tokenizer->consumeNextToken().Value;
return true;
case TokenInfo::TK_Ident:
return parseIdentifierPrefixImpl(Value);
case TokenInfo::TK_CodeCompletion:
addExpressionCompletions();
return false;
case TokenInfo::TK_Eof:
Error->addError(Tokenizer->consumeNextToken().Range,
Error->ET_ParserNoCode);
return false;
case TokenInfo::TK_Error:
// This error was already reported by the tokenizer.
return false;
case TokenInfo::TK_OpenParen:
case TokenInfo::TK_CloseParen:
case TokenInfo::TK_Comma:
case TokenInfo::TK_Period:
case TokenInfo::TK_InvalidChar:
const TokenInfo Token = Tokenizer->consumeNextToken();
Error->addError(Token.Range, Error->ET_ParserInvalidToken) << Token.Text;
return false;
}
llvm_unreachable("Unknown token kind.");
}
static llvm::ManagedStatic<Parser::RegistrySema> DefaultRegistrySema;
Parser::Parser(CodeTokenizer *Tokenizer, Sema *S,
const NamedValueMap *NamedValues, Diagnostics *Error)
: Tokenizer(Tokenizer), S(S ? S : &*DefaultRegistrySema),
NamedValues(NamedValues), Error(Error) {}
Parser::RegistrySema::~RegistrySema() = default;
llvm::Optional<MatcherCtor>
Parser::RegistrySema::lookupMatcherCtor(StringRef MatcherName) {
return Registry::lookupMatcherCtor(MatcherName);
}
VariantMatcher Parser::RegistrySema::actOnMatcherExpression(
MatcherCtor Ctor, SourceRange NameRange, StringRef BindID,
ArrayRef<ParserValue> Args, Diagnostics *Error) {
if (BindID.empty()) {
return Registry::constructMatcher(Ctor, NameRange, Args, Error);
} else {
return Registry::constructBoundMatcher(Ctor, NameRange, BindID, Args,
Error);
}
}
std::vector<ArgKind> Parser::RegistrySema::getAcceptedCompletionTypes(
ArrayRef<std::pair<MatcherCtor, unsigned>> Context) {
return Registry::getAcceptedCompletionTypes(Context);
}
std::vector<MatcherCompletion> Parser::RegistrySema::getMatcherCompletions(
ArrayRef<ArgKind> AcceptedTypes) {
return Registry::getMatcherCompletions(AcceptedTypes);
}
bool Parser::parseExpression(StringRef Code, Sema *S,
const NamedValueMap *NamedValues,
VariantValue *Value, Diagnostics *Error) {
CodeTokenizer Tokenizer(Code, Error);
if (!Parser(&Tokenizer, S, NamedValues, Error).parseExpressionImpl(Value))
return false;
if (Tokenizer.peekNextToken().Kind != TokenInfo::TK_Eof) {
Error->addError(Tokenizer.peekNextToken().Range,
Error->ET_ParserTrailingCode);
return false;
}
return true;
}
std::vector<MatcherCompletion>
Parser::completeExpression(StringRef Code, unsigned CompletionOffset, Sema *S,
const NamedValueMap *NamedValues) {
Diagnostics Error;
CodeTokenizer Tokenizer(Code, &Error, CompletionOffset);
Parser P(&Tokenizer, S, NamedValues, &Error);
VariantValue Dummy;
P.parseExpressionImpl(&Dummy);
// Sort by specificity, then by name.
llvm::sort(P.Completions,
[](const MatcherCompletion &A, const MatcherCompletion &B) {
if (A.Specificity != B.Specificity)
return A.Specificity > B.Specificity;
return A.TypedText < B.TypedText;
});
return P.Completions;
}
llvm::Optional<DynTypedMatcher>
Parser::parseMatcherExpression(StringRef Code, Sema *S,
const NamedValueMap *NamedValues,
Diagnostics *Error) {
VariantValue Value;
if (!parseExpression(Code, S, NamedValues, &Value, Error))
return llvm::Optional<DynTypedMatcher>();
if (!Value.isMatcher()) {
Error->addError(SourceRange(), Error->ET_ParserNotAMatcher);
return llvm::Optional<DynTypedMatcher>();
}
llvm::Optional<DynTypedMatcher> Result =
Value.getMatcher().getSingleMatcher();
if (!Result.hasValue()) {
Error->addError(SourceRange(), Error->ET_ParserOverloadedType)
<< Value.getTypeAsString();
}
return Result;
}
} // namespace dynamic
} // namespace ast_matchers
} // namespace clang
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