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lexer.cpp
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lexer.cpp
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#include "lexer.hpp"
#include <cctype>
#include <cstdlib>
#include <optional>
#include <string>
#include <string_view>
#include <components/fx/lexer_types.hpp>
#include <components/misc/strings/format.hpp>
namespace fx
{
namespace Lexer
{
Lexer::Lexer(std::string_view buffer)
: mHead(buffer.data())
, mTail(mHead + buffer.length())
, mAbsolutePos(0)
, mColumn(0)
, mLine(0)
, mBuffer(buffer)
, mLastToken(Eof{})
{
}
Token Lexer::next()
{
if (mLookahead)
{
auto token = *mLookahead;
drop();
return token;
}
mLastToken = scanToken();
return mLastToken;
}
Token Lexer::peek()
{
if (!mLookahead)
mLookahead = scanToken();
return *mLookahead;
}
void Lexer::drop()
{
mLookahead = std::nullopt;
}
std::optional<std::string_view> Lexer::jump()
{
bool multi = false;
bool single = false;
auto start = mHead;
std::size_t level = 1;
mLastJumpBlock.line = mLine;
if (head() == '}')
{
mLastJumpBlock.content = {};
return mLastJumpBlock.content;
}
for (; mHead != mTail; advance())
{
if (head() == '\n')
{
mLine++;
mColumn = 0;
if (single)
{
single = false;
continue;
}
}
else if (multi && head() == '*' && peekChar('/'))
{
multi = false;
advance();
continue;
}
else if (multi || single)
{
continue;
}
else if (head() == '/' && peekChar('/'))
{
single = true;
advance();
continue;
}
else if (head() == '/' && peekChar('*'))
{
multi = true;
advance();
continue;
}
if (head() == '{')
level++;
else if (head() == '}')
level--;
if (level == 0)
{
mHead--;
mLine--;
auto sv = std::string_view{ start, static_cast<std::string_view::size_type>(mHead + 1 - start) };
mLastJumpBlock.content = sv;
return sv;
}
}
mLastJumpBlock = {};
return std::nullopt;
}
Lexer::Block Lexer::getLastJumpBlock() const
{
return mLastJumpBlock;
}
[[noreturn]] void Lexer::error(const std::string& msg)
{
throw LexerException(Misc::StringUtils::format("Line %zu Col %zu. %s", mLine + 1, mColumn, msg));
}
void Lexer::advance()
{
mAbsolutePos++;
mHead++;
mColumn++;
}
char Lexer::head()
{
return *mHead;
}
bool Lexer::peekChar(char c)
{
if (mHead == mTail)
return false;
return *(mHead + 1) == c;
}
Token Lexer::scanToken()
{
while (true)
{
if (mHead == mTail)
return { Eof{} };
if (head() == '\n')
{
mLine++;
mColumn = 0;
}
if (!std::isspace(head()))
break;
advance();
}
if (head() == '\"')
return scanStringLiteral();
if (std::isalpha(head()))
return scanLiteral();
if (std::isdigit(head()) || head() == '.' || head() == '-')
return scanNumber();
switch (head())
{
case '=':
advance();
return { Equal{} };
case '{':
advance();
return { Open_bracket{} };
case '}':
advance();
return { Close_bracket{} };
case '(':
advance();
return { Open_Parenthesis{} };
case ')':
advance();
return { Close_Parenthesis{} };
case '\"':
advance();
return { Quote{} };
case ':':
advance();
return { Colon{} };
case ';':
advance();
return { SemiColon{} };
case '|':
advance();
return { VBar{} };
case ',':
advance();
return { Comma{} };
default:
error(Misc::StringUtils::format("unexpected token <%c>", head()));
}
}
Token Lexer::scanLiteral()
{
auto start = mHead;
advance();
while (mHead != mTail && (std::isalnum(head()) || head() == '_'))
advance();
std::string_view value{ start, static_cast<std::string_view::size_type>(mHead - start) };
if (value == "shared")
return Shared{};
if (value == "technique")
return Technique{};
if (value == "render_target")
return Render_Target{};
if (value == "vertex")
return Vertex{};
if (value == "fragment")
return Fragment{};
if (value == "compute")
return Compute{};
if (value == "sampler_1d")
return Sampler_1D{};
if (value == "sampler_2d")
return Sampler_2D{};
if (value == "sampler_3d")
return Sampler_3D{};
if (value == "uniform_bool")
return Uniform_Bool{};
if (value == "uniform_float")
return Uniform_Float{};
if (value == "uniform_int")
return Uniform_Int{};
if (value == "uniform_vec2")
return Uniform_Vec2{};
if (value == "uniform_vec3")
return Uniform_Vec3{};
if (value == "uniform_vec4")
return Uniform_Vec4{};
if (value == "true")
return True{};
if (value == "false")
return False{};
if (value == "vec2")
return Vec2{};
if (value == "vec3")
return Vec3{};
if (value == "vec4")
return Vec4{};
return Literal{ value };
}
Token Lexer::scanStringLiteral()
{
advance(); // consume quote
auto start = mHead;
bool terminated = false;
for (; mHead != mTail; advance())
{
if (head() == '\"')
{
terminated = true;
advance();
break;
}
}
if (!terminated)
error("unterminated string");
return String{ { start, static_cast<std::string_view::size_type>(mHead - start - 1) } };
}
Token Lexer::scanNumber()
{
double buffer;
char* endPtr;
buffer = std::strtod(mHead, &endPtr);
if (endPtr == nullptr)
error("critical error while parsing number");
const char* tmp = mHead;
mHead = endPtr;
for (; tmp != endPtr; ++tmp)
{
if ((*tmp == '.'))
return Float{ static_cast<float>(buffer) };
}
return Integer{ static_cast<int>(buffer) };
}
}
}