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scanner.cc
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scanner.cc
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#include <tree_sitter/parser.h>
#include <vector>
#include <cwctype>
#include <cassert>
namespace {
using std::vector;
enum TokenType {
NEWLINE,
INDENT,
DEDENT,
};
struct Scanner {
Scanner() {
deserialize(NULL, 0);
}
unsigned serialize(char *buffer) {
size_t i = 0;
buffer[i++] = queued_dedent_count;
vector<uint16_t>::iterator
iter = indent_length_stack.begin() + 1,
end = indent_length_stack.end();
for (; iter != end && i < TREE_SITTER_SERIALIZATION_BUFFER_SIZE; ++iter) {
buffer[i++] = *iter;
}
return i;
}
void deserialize(const char *buffer, unsigned length) {
queued_dedent_count = 0;
indent_length_stack.clear();
indent_length_stack.push_back(0);
if (length > 0) {
size_t i = 0;
queued_dedent_count = buffer[i++];
while (i < length) indent_length_stack.push_back(buffer[i++]);
}
}
void advance(TSLexer *lexer) {
lexer->advance(lexer, false);
}
// returns True if newline \n were skipped
bool skipJunk(TSLexer *lexer) {
bool skippedNewline = false;
while (lexer->lookahead == ' ' || lexer->lookahead == '\t' || lexer->lookahead == '\r' || lexer->lookahead == '\n') {
if (lexer->lookahead == '\n') {
skippedNewline = true;
lexer->advance(lexer, true);
// mark the end of the last lexeme
lexer->mark_end(lexer);
} else {
lexer->advance(lexer, true);
}
}
return skippedNewline;
}
bool scan(TSLexer *lexer, const bool *valid_symbols) {
bool skippedNewline = false;
if (valid_symbols[DEDENT] && queued_dedent_count > 0) {
queued_dedent_count--;
lexer->result_symbol = DEDENT;
return true;
}
// skip spaces and newline
skippedNewline = skippedNewline || skipJunk(lexer);
// in case of EOF
if (lexer->lookahead == 0) {
if (valid_symbols[DEDENT] && indent_length_stack.size() > 1) {
indent_length_stack.pop_back();
lexer->result_symbol = DEDENT;
return true;
}
if (valid_symbols[NEWLINE]) {
lexer->result_symbol = NEWLINE;
return true;
}
return false;
}
// TODO: handle comments
bool next_token_is_comment = false;
uint32_t indent_length = lexer->get_column(lexer);
if (!next_token_is_comment) {
// do
// line0 <newline>
// line1
if (valid_symbols[NEWLINE] && skippedNewline && indent_length == indent_length_stack.back()) {
lexer->result_symbol = NEWLINE;
return true;
}
// do
// line0
// still0
if (valid_symbols[INDENT] && indent_length > indent_length_stack.back()) {
indent_length_stack.push_back(indent_length);
lexer->result_symbol = INDENT;
return true;
}
// do
// line0 <newline>
// line1
if (skippedNewline && indent_length < indent_length_stack.back()) {
lexer->result_symbol = NEWLINE;
return true;
}
// do
// do
// line0
// line1
// ^ here
if (!skippedNewline && indent_length < indent_length_stack.back()) {
indent_length_stack.pop_back();
while (indent_length < indent_length_stack.back()) {
indent_length_stack.pop_back();
queued_dedent_count++;
}
if (valid_symbols[DEDENT]) {
lexer->result_symbol = DEDENT;
return true;
} else {
queued_dedent_count++;
}
}
}
return false;
}
vector<uint16_t> indent_length_stack;
uint32_t queued_dedent_count;
};
}
extern "C" {
void *tree_sitter_agda_external_scanner_create() {
return new Scanner();
}
bool tree_sitter_agda_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_agda_external_scanner_serialize(void *payload, char *buffer) {
Scanner *scanner = static_cast<Scanner *>(payload);
return scanner->serialize(buffer);
}
void tree_sitter_agda_external_scanner_deserialize(void *payload,
const char *buffer,
unsigned length) {
Scanner *scanner = static_cast<Scanner *>(payload);
scanner->deserialize(buffer, length);
}
void tree_sitter_agda_external_scanner_destroy(void *payload) {
Scanner *scanner = static_cast<Scanner *>(payload);
delete scanner;
}
}