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LibCpp: Start working on a C preprocessor

We currently handle basic #define statements as well as ifdef and else
branches.
This commit is contained in:
Itamar 2021-02-06 15:51:04 +02:00 committed by Andreas Kling
parent 2d2b3ba5ed
commit bed3261723
5 changed files with 283 additions and 0 deletions

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@ -2,6 +2,7 @@ set(SOURCES
AST.cpp
Lexer.cpp
Parser.cpp
Preprocessor.cpp
SyntaxHighlighter.cpp
)

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@ -0,0 +1,170 @@
/*
* Copyright (c) 2021, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "Preprocessor.h"
#include <AK/Assertions.h>
#include <AK/GenericLexer.h>
#include <AK/StringBuilder.h>
#include <ctype.h>
namespace Cpp {
Preprocessor::Preprocessor(const StringView& program)
: m_program(program)
{
m_lines = m_program.split_view('\n', true);
}
const String& Preprocessor::process()
{
for (; m_line_index < m_lines.size(); ++m_line_index) {
auto& line = m_lines[m_line_index];
if (line.starts_with("#")) {
handle_preprocessor_line(line);
} else if (m_state == State::Normal) {
m_builder.append(line);
}
m_builder.append("\n");
}
m_processed_text = m_builder.to_string();
return m_processed_text;
}
void Preprocessor::handle_preprocessor_line(const StringView& line)
{
GenericLexer lexer(line);
auto consume_whitespace = [&] {
lexer.ignore_while([](char ch) { return isspace(ch); });
if (lexer.peek() == '/' && lexer.peek(1) == '/')
lexer.ignore_until([](char ch) { return ch == '\n'; });
};
consume_whitespace();
lexer.consume_specific('#');
consume_whitespace();
auto keyword = lexer.consume_until(' ');
if (keyword == "include") {
consume_whitespace();
m_included_paths.append(lexer.consume_all());
return;
}
if (keyword == "else") {
ASSERT(m_current_depth > 0);
if (m_depths_of_not_taken_branches.contains_slow(m_current_depth - 1)) {
m_depths_of_not_taken_branches.remove_all_matching([this](auto x) { return x == m_current_depth - 1; });
m_state = State::Normal;
}
if (m_depths_of_taken_branches.contains_slow(m_current_depth - 1)) {
m_depths_of_taken_branches.contains_slow(m_current_depth - 1);
m_state = State::SkipElseBranch;
}
return;
}
if (keyword == "endif") {
ASSERT(m_current_depth > 0);
--m_current_depth;
if (m_depths_of_not_taken_branches.contains_slow(m_current_depth)) {
m_depths_of_not_taken_branches.remove_all_matching([this](auto x) { return x == m_current_depth; });
}
if (m_depths_of_taken_branches.contains_slow(m_current_depth)) {
m_depths_of_taken_branches.contains_slow(m_current_depth);
}
m_state = State::Normal;
return;
}
if (keyword == "define") {
if (m_state == State::Normal) {
auto key = lexer.consume_until(' ');
consume_whitespace();
DefinedValue value;
auto string_value = lexer.consume_all();
if (!string_value.is_empty())
value.value = string_value;
m_definitions.set(key, value);
}
return;
}
if (keyword == "undef") {
if (m_state == State::Normal) {
auto key = lexer.consume_until(' ');
lexer.consume_all();
m_definitions.remove(key);
}
return;
}
if (keyword == "ifdef") {
++m_current_depth;
if (m_state == State::Normal) {
auto key = lexer.consume_until(' ');
if (m_definitions.contains(key)) {
m_depths_of_taken_branches.append(m_current_depth - 1);
return;
} else {
m_depths_of_not_taken_branches.append(m_current_depth - 1);
m_state = State::SkipIfBranch;
return;
}
}
return;
}
if (keyword == "ifndef") {
++m_current_depth;
if (m_state == State::Normal) {
auto key = lexer.consume_until(' ');
if (!m_definitions.contains(key)) {
m_depths_of_taken_branches.append(m_current_depth - 1);
return;
} else {
m_depths_of_not_taken_branches.append(m_current_depth - 1);
m_state = State::SkipIfBranch;
return;
}
}
return;
}
if (keyword == "if") {
++m_current_depth;
if (m_state == State::Normal) {
// FIXME: Implement #if logic
// We currently always take #if branches.
m_depths_of_taken_branches.append(m_current_depth - 1);
}
return;
}
if (keyword == "pragma") {
lexer.consume_all();
return;
}
dbgln("Unsupported preprocessor keyword: {}", keyword);
ASSERT_NOT_REACHED();
}
};

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@ -0,0 +1,70 @@
/*
* Copyright (c) 2021, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/HashMap.h>
#include <AK/Optional.h>
#include <AK/String.h>
#include <AK/StringView.h>
#include <AK/Vector.h>
namespace Cpp {
class Preprocessor {
public:
explicit Preprocessor(const StringView&);
const String& process();
const String& processed_text();
Vector<StringView> included_paths() const { return m_included_paths; }
private:
struct DefinedValue {
Optional<StringView> value;
};
void handle_preprocessor_line(const StringView&);
HashMap<StringView, DefinedValue> m_definitions;
const StringView m_program;
StringBuilder m_builder;
Vector<StringView> m_lines;
size_t m_line_index { 0 };
size_t m_current_depth { 0 };
Vector<size_t> m_depths_of_taken_branches;
Vector<size_t> m_depths_of_not_taken_branches;
enum class State {
Normal,
SkipIfBranch,
SkipElseBranch
};
State m_state { State::Normal };
Vector<StringView> m_included_paths;
String m_processed_text;
};
}

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@ -49,3 +49,4 @@ target_link_libraries(tt LibPthread)
target_link_libraries(grep LibRegex)
target_link_libraries(gunzip LibCompress)
target_link_libraries(CppParserTest LibCpp LibGUI)
target_link_libraries(PreprocessorTest LibCpp LibGUI)

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@ -0,0 +1,41 @@
/*
* Copyright (c) 2021, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "AK/Forward.h"
#include <LibCore/File.h>
#include <LibCpp/Preprocessor.h>
int main(int, char**)
{
auto file = Core::File::construct("/home/anon/Source/little/other.h");
if (!file->open(Core::IODevice::ReadOnly)) {
perror("open");
exit(1);
}
auto content = file->read_all();
Cpp::Preprocessor cpp(StringView { content });
dbgprintf("%s\n", cpp.process().characters());
}