Refactor parser error messages

- move message generation to TSParseError,
  so that Parser doesn’t need to import <string>, and can
  be compiled as plain C.

src/runtime/parser.cpp

@@ -1,127 +0,0 @@
-#include "parser.h"
-#include <stdio.h>
-#include <string>
-
-using std::string;
-using std::to_string;
-
-#define TS_DEBUG_PARSE
-#define TS_DEBUG_LEX
-
-#ifdef TS_DEBUG_LEX
-#define DEBUG_LEX(...) fprintf(stderr, __VA_ARGS__)
-#else
-#define DEBUG_LEX(...)
-#endif
-
-#ifdef TS_DEBUG_PARSE
-#define DEBUG_PARSE(...) fprintf(stderr, __VA_ARGS__)
-#else
-#define DEBUG_PARSE(...)
-#endif
-
-static int INITIAL_STACK_SIZE = 100;
-
-struct TSStackEntry {
-    TSState state;
-    TSTree *node;
-};
-
-TSParser TSParserMake(const char *input) {
-    TSParser result = {
-        .tree = NULL,
-        .input = input,
-        .error_message = NULL,
-        .position = 0,
-        .lookahead_node = NULL,
-        .lex_state = 0,
-        .stack = (TSStackEntry *)calloc(INITIAL_STACK_SIZE, sizeof(TSStackEntry)),
-        .stack_size = 0,
-    };
-    return result;
-}
-
-void TSParserShift(TSParser *parser, TSState parse_state) {
-    DEBUG_PARSE("shift %d \n", parse_state);
-    TSStackEntry *entry = (parser->stack + parser->stack_size);
-    entry->state = parse_state;
-    entry->node = parser->lookahead_node;
-    parser->lookahead_node = NULL;
-    parser->stack_size++;
-}
-
-void TSParserReduce(TSParser *parser, TSSymbol symbol, int child_count) {
-    parser->stack_size -= child_count;
-
-    TSTree **children = (TSTree **)malloc(child_count * sizeof(TSTree *));
-    for (int i = 0; i < child_count; i++) {
-        children[i] = parser->stack[parser->stack_size + i].node;
-    }
-    
-    parser->lookahead_node = TSTreeMake(symbol, child_count, children);
-    DEBUG_PARSE("reduce: %ld, state: %u \n", symbol, TSParserParseState(parser));
-}
-
-void TSParserError(TSParser *parser, size_t count, const char **expected_inputs) {
-    string result = "Unexpected token " + to_string(TSParserLookaheadSym(parser)) + ". ";
-    result += "Expected tokens:";
-    for (int i = 0; i < count; i++)
-        result += string(" '") + expected_inputs[i] + "'";
-    char *stuff = (char *)malloc(result.size() * sizeof(char));
-    strcpy(stuff, result.c_str());
-    parser->error_message = stuff;
-}
-
-void TSParserLexError(TSParser *parser, size_t count, const char **expected_inputs) {
-    string result = string("Unexpected character '") + TSParserLookaheadChar(parser) + "'. ";
-    result += "Expected characters:";
-    for (int i = 0; i < count; i++)
-        result += string(" ") + expected_inputs[i] + "";
-    char *stuff = (char *)malloc(result.size() * sizeof(char));
-    strcpy(stuff, result.c_str());
-    parser->error_message = stuff;
-}
-
-void TSParserAdvance(TSParser *parser, TSState lex_state) {
-    DEBUG_LEX("character: '%c' \n", TSParserLookaheadChar(parser));
-    parser->position++;
-    parser->lex_state = lex_state;
-}
-
-char TSParserLookaheadChar(const TSParser *parser) {
-    return parser->input[parser->position];
-}
-
-long TSParserLookaheadSym(const TSParser *parser) {
-    TSTree *node = parser->lookahead_node;
-    return node ? node->value : -1;
-}
-
-void TSParserSetLookaheadSym(TSParser *parser, TSSymbol symbol) {
-    DEBUG_LEX("token: %ld \n", symbol);
-    parser->lookahead_node = TSTreeMake(symbol, 0, NULL);
-}
-
-TSState TSParserParseState(const TSParser *parser) {
-    return parser->stack[parser->stack_size - 1].state;
-}
-
-TSState TSParserLexState(const TSParser *parser) {
-    return parser->lex_state;
-}
-
-void TSParserSetLexState(TSParser *parser, TSState lex_state) {
-    parser->lex_state = lex_state;
-}
-
-void TSParserAcceptInput(TSParser *parser) {
-    parser->tree = parser->stack[parser->stack_size - 1].node;
-}
-
-TSParseResult TSParserResult(TSParser *parser) {
-    TSParseResult result = {
-        .tree = parser->tree,
-        .error = { .position = parser->position, .message = parser->error_message }
-    };
-    return result;
-}