tree-sitter-html/src/scanner.cc

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#include <tree_sitter/parser.h>
#include <algorithm>
#include <vector>
#include <string>
#include <locale>
#include "tag.h"
namespace {
using std::vector;
using std::string;
enum TokenType {
OPEN_START_TAG,
CLOSE_START_TAG,
SELF_CLOSE_START_TAG,
END_TAG,
IMPLICIT_END_TAG,
ERRONEOUS_END_TAG,
COMMENT,
};
struct Scanner {
Scanner() {}
unsigned serialize(char *buffer) {
unsigned i = 0;
for (Tag &tag : tags) {
buffer[i] = static_cast<char>(tag.type);
i++;
if (tag.type == CUSTOM) {
buffer[i++] = tag.custom_tag_name.size();
for (char c : tag.custom_tag_name) {
buffer[i++] = c;
}
}
}
return i;
}
void deserialize(const char *buffer, unsigned length) {
tags.clear();
unsigned i = 0;
while (i < length) {
Tag tag { static_cast<TagType>(buffer[i]), "" };
i++;
if (tag.type == CUSTOM) {
tag.custom_tag_name.resize(buffer[i++]);
for (unsigned j = 0; j < tag.custom_tag_name.size(); j++) {
tag.custom_tag_name[j] = buffer[i++];
}
}
tags.push_back(tag);
}
}
string scan_tag_name(TSLexer *lexer) {
string tag_name;
while (iswalpha(lexer->lookahead) || lexer->lookahead == '-' || lexer->lookahead == ':') {
tag_name += std::toupper(lexer->lookahead);
lexer->advance(lexer, false);
}
return tag_name;
}
bool comment(TSLexer *lexer) {
if (lexer->lookahead != '-') return false;
lexer->advance(lexer, false);
if (lexer->lookahead != '-') return false;
lexer->advance(lexer, false);
unsigned dashes = 0;
auto c = lexer->lookahead;
while (c) {
switch (c) {
case '-':
++dashes;
break;
case '>':
if (dashes >= 2) {
lexer->result_symbol = COMMENT;
lexer->advance(lexer, false);
lexer->mark_end(lexer);
return true;
}
break;
default:
dashes = 0;
}
lexer->advance(lexer, false);
c = lexer->lookahead;
}
return false;
}
bool start_tag(TSLexer *lexer) {
if (!tags.empty() && tags.back().is_void()) {
tags.pop_back();
lexer->result_symbol = IMPLICIT_END_TAG;
return true;
}
auto tag_name = scan_tag_name(lexer);
if (tag_name.empty()) return false;
Tag tag = Tag::for_name(tag_name);
tags.push_back(tag);
lexer->mark_end(lexer);
lexer->result_symbol = OPEN_START_TAG;
return true;
}
bool end_tag(TSLexer *lexer) {
auto tag_name = scan_tag_name(lexer);
if (tag_name.empty()) return false;
lexer->advance(lexer, false);
Tag tag = Tag::for_name(tag_name);
// The tag correctly closes the topmost element on the stack
if (tag == tags.back()) {
tags.pop_back();
lexer->mark_end(lexer);
lexer->result_symbol = END_TAG;
return true;
}
// Otherwise, dig deeper and queue implicit end tags (to be nice in
// the case of malformed HTML)
if (std::find(tags.begin(), tags.end(), tag) != tags.end()) {
tags.pop_back();
lexer->result_symbol = IMPLICIT_END_TAG;
return true;
}
// You closed a tag you never opened 😭
lexer->mark_end(lexer);
lexer->result_symbol = ERRONEOUS_END_TAG;
return true;
}
bool scan(TSLexer *lexer, const bool *valid_symbols) {
while (iswspace(lexer->lookahead)) {
lexer->advance(lexer, true);
}
switch (lexer->lookahead) {
case '<':
lexer->mark_end(lexer);
lexer->advance(lexer, false);
if (lexer->lookahead == '!') {
lexer->advance(lexer, false);
return comment(lexer);
}
if (valid_symbols[OPEN_START_TAG] || valid_symbols[END_TAG]) {
if (lexer->lookahead == '/') {
lexer->advance(lexer, false);
return end_tag(lexer);
}
return start_tag(lexer);
}
break;
case '>':
if (valid_symbols[CLOSE_START_TAG]) {
lexer->advance(lexer, false);
lexer->result_symbol = CLOSE_START_TAG;
return true;
}
break;
case '/':
if (valid_symbols[SELF_CLOSE_START_TAG]) {
lexer->advance(lexer, false);
if (lexer->lookahead == '>') {
lexer->advance(lexer, false);
tags.pop_back();
lexer->result_symbol = SELF_CLOSE_START_TAG;
return true;
}
}
break;
}
return false;
}
vector<Tag> tags;
};
}
extern "C" {
void *tree_sitter_html_external_scanner_create() {
return new Scanner();
}
bool tree_sitter_html_external_scanner_scan(void *payload, TSLexer *lexer,
const bool *valid_symbols) {
Scanner *scanner = static_cast<Scanner *>(payload);
return scanner->scan(lexer, valid_symbols);
}
unsigned tree_sitter_html_external_scanner_serialize(void *payload, char *buffer) {
Scanner *scanner = static_cast<Scanner *>(payload);
return scanner->serialize(buffer);
}
void tree_sitter_html_external_scanner_deserialize(void *payload, const char *buffer, unsigned length) {
Scanner *scanner = static_cast<Scanner *>(payload);
scanner->deserialize(buffer, length);
}
void tree_sitter_html_external_scanner_destroy(void *payload) {
Scanner *scanner = static_cast<Scanner *>(payload);
delete scanner;
}
}