rawsql-ts
Version:
[beta]High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.
38 lines • 1.83 kB
JavaScript
import { OffsetClause } from "../models/Clause";
import { SqlTokenizer } from "./SqlTokenizer";
import { ValueParser } from "./ValueParser";
export class OffsetClauseParser {
// Parse SQL string to AST (was: parse)
static parse(query) {
const tokenizer = new SqlTokenizer(query); // Initialize tokenizer
const lexemes = tokenizer.readLexmes(); // Get tokens
// 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 OFFSET clause is complete but there are additional tokens.`);
}
return result.value;
}
// Parse from lexeme array (was: parse)
static parseFromLexeme(lexemes, index) {
let idx = index;
if (lexemes[idx].value !== 'offset') {
throw new Error(`Syntax error at position ${idx}: Expected 'OFFSET' keyword but found "${lexemes[idx].value}". OFFSET clauses must start with the OFFSET keyword.`);
}
idx++;
if (idx >= lexemes.length) {
throw new Error(`Syntax error: Unexpected end of input after 'OFFSET' keyword. The OFFSET clause requires a numeric expression.`);
}
// Parse OFFSET value
const offsetItem = ValueParser.parseFromLexeme(lexemes, idx);
idx = offsetItem.newIndex;
// If there is a "row" or "rows" command, skip it
if (idx < lexemes.length && (lexemes[idx].value === 'row' || lexemes[idx].value === 'rows')) {
idx++;
}
const clause = new OffsetClause(offsetItem.value);
return { value: clause, newIndex: idx };
}
}
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