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//===-- DILLexer.cpp ------------------------------------------------------===//
//
// 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
//
// This implements the recursive descent parser for the Data Inspection
// Language (DIL), and its helper functions, which will eventually underlie the
// 'frame variable' command. The language that this parser recognizes is
// described in lldb/docs/dil-expr-lang.ebnf
//
//===----------------------------------------------------------------------===//
#include "lldb/ValueObject/DILLexer.h"
#include "lldb/Utility/Status.h"
#include "lldb/ValueObject/DILParser.h"
#include "llvm/ADT/StringSwitch.h"
namespace lldb_private::dil {
llvm::StringRef Token::GetTokenName(Kind kind) {
switch (kind) {
case Kind::amp:
return "amp";
case Kind::arrow:
return "arrow";
case Kind::coloncolon:
return "coloncolon";
case Kind::eof:
return "eof";
case Kind::identifier:
return "identifier";
case Kind::l_paren:
return "l_paren";
case Kind::l_square:
return "l_square";
case Kind::minus:
return "minus";
case Kind::numeric_constant:
return "numeric_constant";
case Kind::period:
return "period";
case Kind::r_paren:
return "r_paren";
case Kind::r_square:
return "r_square";
case Token::star:
return "star";
}
llvm_unreachable("Unknown token name");
}
static bool IsLetter(char c) {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
}
static bool IsDigit(char c) { return '0' <= c && c <= '9'; }
// A word starts with a letter, underscore, or dollar sign, followed by
// letters ('a'..'z','A'..'Z'), digits ('0'..'9'), and/or underscores.
static std::optional<llvm::StringRef> IsWord(llvm::StringRef expr,
llvm::StringRef &remainder) {
// Find the longest prefix consisting of letters, digits, underscors and
// '$'. If it doesn't start with a digit, then it's a word.
llvm::StringRef candidate = remainder.take_while(
[](char c) { return IsDigit(c) || IsLetter(c) || c == '_' || c == '$'; });
if (candidate.empty() || IsDigit(candidate[0]))
return std::nullopt;
remainder = remainder.drop_front(candidate.size());
return candidate;
}
static bool IsNumberBodyChar(char ch) { return IsDigit(ch) || IsLetter(ch); }
static std::optional<llvm::StringRef> IsNumber(llvm::StringRef expr,
llvm::StringRef &remainder) {
if (IsDigit(remainder[0])) {
llvm::StringRef number = remainder.take_while(IsNumberBodyChar);
remainder = remainder.drop_front(number.size());
return number;
}
return std::nullopt;
}
llvm::Expected<DILLexer> DILLexer::Create(llvm::StringRef expr) {
std::vector<Token> tokens;
llvm::StringRef remainder = expr;
do {
if (llvm::Expected<Token> t = Lex(expr, remainder)) {
tokens.push_back(std::move(*t));
} else {
return t.takeError();
}
} while (tokens.back().GetKind() != Token::eof);
return DILLexer(expr, std::move(tokens));
}
llvm::Expected<Token> DILLexer::Lex(llvm::StringRef expr,
llvm::StringRef &remainder) {
// Skip over whitespace (spaces).
remainder = remainder.ltrim();
llvm::StringRef::iterator cur_pos = remainder.begin();
// Check to see if we've reached the end of our input string.
if (remainder.empty())
return Token(Token::eof, "", (uint32_t)expr.size());
uint32_t position = cur_pos - expr.begin();
std::optional<llvm::StringRef> maybe_number = IsNumber(expr, remainder);
if (maybe_number)
return Token(Token::numeric_constant, maybe_number->str(), position);
std::optional<llvm::StringRef> maybe_word = IsWord(expr, remainder);
if (maybe_word)
return Token(Token::identifier, maybe_word->str(), position);
constexpr std::pair<Token::Kind, const char *> operators[] = {
{Token::amp, "&"}, {Token::arrow, "->"}, {Token::coloncolon, "::"},
{Token::l_paren, "("}, {Token::l_square, "["}, {Token::minus, "-"},
{Token::period, "."}, {Token::r_paren, ")"}, {Token::r_square, "]"},
{Token::star, "*"},
};
for (auto [kind, str] : operators) {
if (remainder.consume_front(str))
return Token(kind, str, position);
}
// Unrecognized character(s) in string; unable to lex it.
return llvm::make_error<DILDiagnosticError>(expr, "unrecognized token",
position);
}
} // namespace lldb_private::dil
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