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#include "CodegenLexer.hpp"
#include <cassert>
bool StbTokenIsSingleChar(int lexerToken) {
return lexerToken >= 0 && lexerToken < 256;
}
bool StbTokenIsMultiChar(int lexerToken) {
return !StbTokenIsMultiChar(lexerToken);
}
std::string CombineTokens(std::span<const StbLexerToken> tokens) {
size_t length = 0;
for (auto& token : tokens) {
length += token.text.size();
}
std::string result;
result.reserve(length);
for (auto& token : tokens) {
result += token.text;
}
return result;
}
const StbLexerToken& CodegenLexer::Current() const {
assert(idx < tokens.size());
return tokens[idx];
}
void CodegenLexer::InitializeFrom(std::string_view source) {
this->tokens = {};
this->idx = 0;
stb_lexer lexer;
char stringStorage[65536];
const char* srcBegin = source.data();
const char* srcEnd = srcBegin + source.length();
stb_c_lexer_init(&lexer, srcBegin, srcEnd, stringStorage, sizeof(stringStorage));
struct TokenCombiningPattern {
StbLexerToken result;
char matchChars[16];
};
const TokenCombiningPattern kDoubleColon = {
.result = {
.text = "::",
.type = CLEX_ext_double_colon,
},
.matchChars = { ':', ':', '\0' },
};
const TokenCombiningPattern kDotDotDot = {
.result = {
.text = "...",
.type = CLEX_ext_dot_dot_dot,
},
.matchChars = { '.', '.', '.', '\0' },
};
const TokenCombiningPattern* currentState = nullptr;
int currentStateCharIdx = 0;
while (true) {
// See stb_c_lexer.h's comments, here are a few additinos that aren't made clear in the file:
// - `lexer->token` (noted as "token" below) after calling stb_c_lexer_get_token() contains either:
// 1. 0 <= token < 256: an ASCII character (more precisely a single char that the lexer ate; technically can be an incomplete code unit)
// 2. token < 0: an unknown token
// 3. One of the `CLEX_*` enums: a special, recognized token such as an operator
int stbToken = stb_c_lexer_get_token(&lexer);
if (stbToken == 0) {
// EOF
break;
}
if (lexer.token == CLEX_parse_error) {
printf("[ERROR] stb_c_lexer countered a parse error.\n");
// TODO how to handle?
continue;
}
StbLexerToken token;
if (StbTokenIsSingleChar(lexer.token)) {
char c = lexer.token;
token.type = CLEX_ext_single_char;
token.text = std::string(1, c);
if (!currentState) {
#define TRY_START_MATCH(states) \
if (states.matchChars[0] == c) { \
currentState = &states; \
currentStateCharIdx = 1; \
}
TRY_START_MATCH(kDoubleColon);
TRY_START_MATCH(kDotDotDot);
#undef TRY_START_MATCH
} else {
if (currentState->matchChars[currentStateCharIdx] == c) {
// Match success
++currentStateCharIdx;
// If we matched all of the chars...
if (currentState->matchChars[currentStateCharIdx] == '\0') {
// We matched (currentStateCharIdx) tokens though this one is pushed into the vector, leaving (currentStateCharIdx - 1) tokens to be removed
for (int i = 0, count = currentStateCharIdx - 1; i < count; ++i) {
tokens.pop_back();
}
// Set the current token to desired result
token = currentState->result;
currentState = nullptr;
currentStateCharIdx = 0;
}
} else {
// Match fail, reset
currentState = nullptr;
currentStateCharIdx = 0;
}
}
} else {
token.type = lexer.token;
// WORKAROUND: use null terminated string, stb_c_lexer doens't set string_len properly when parsing identifiers
token.text = std::string(lexer.string);
switch (token.type) {
case CLEX_intlit:
token.lexerIntNumber = lexer.int_number;
break;
case CLEX_floatlit:
token.lexerRealNumber = lexer.real_number;
break;
}
}
tokens.push_back(std::move(token));
token = {};
}
}
const StbLexerToken* CodegenLexer::TryConsumeToken(int type) {
auto& token = tokens[idx];
if (token.type == type) {
++idx;
return &token;
}
return nullptr;
}
const StbLexerToken* CodegenLexer::TryConsumeSingleCharToken(char c) {
auto& token = tokens[idx];
if (token.type == CLEX_ext_single_char &&
token.text[0] == c)
{
++idx;
return &token;
}
return nullptr;
}
void CodegenLexer::SkipUntilToken(int type) {
while (idx < tokens.size()) {
if (Current().type == type) {
break;
}
++idx;
}
}
void CodegenLexer::SkipUntilTokenSingleChar(char c) {
while (idx < tokens.size()) {
auto& curr = Current();
if (curr.type == CLEX_ext_single_char &&
curr.text[0] == c)
{
break;
}
++idx;
}
}
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