rawsql-ts
Version:
[beta]High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.
54 lines • 2.26 kB
JavaScript
import { ForClause, LockMode } from "../models/Clause";
import { SqlTokenizer } from "./SqlTokenizer";
export class ForClauseParser {
// Parse SQL string to AST (was: parse)
static parse(query) {
const tokenizer = new SqlTokenizer(query);
const lexemes = tokenizer.readLexmes();
// Parse
const result = this.parseFromLexeme(lexemes, 0);
// Error if there are remaining tokens
if (result.newIndex < lexemes.length) {
throw new Error(`Syntax error: Unexpected token "${lexemes[result.newIndex].value}" at position ${result.newIndex}. The FOR clause is complete but there are additional tokens.`);
}
return result.value;
}
// Parse from lexeme array (was: parse)
static parseFromLexeme(lexemes, index) {
let idx = index;
// Check for FOR keyword
if (lexemes[idx].value.toLowerCase() !== 'for') {
throw new Error(`Syntax error at position ${idx}: Expected 'FOR' keyword but found "${lexemes[idx].value}". FOR clauses must start with the FOR keyword.`);
}
idx++;
if (idx >= lexemes.length) {
throw new Error(`Syntax error: Unexpected end of input after 'FOR' keyword. The FOR clause requires a lock mode specification.`);
}
// Parse lock mode
const lockModeValue = lexemes[idx].value;
let lockMode;
switch (lockModeValue) {
case 'update':
lockMode = LockMode.Update;
idx++;
break;
case 'share':
lockMode = LockMode.Share;
idx++;
break;
case 'key share':
lockMode = LockMode.KeyShare;
idx++;
break;
case 'no key update':
lockMode = LockMode.NokeyUpdate;
idx++;
break;
default:
throw new Error(`Syntax error at position ${idx}: Invalid lock mode "${lockModeValue}". Valid lock modes are: UPDATE, SHARE, KEY SHARE, NO KEY UPDATE.`);
}
const clause = new ForClause(lockMode);
return { value: clause, newIndex: idx };
}
}
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