rawsql-ts
Version:
[beta]High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.
53 lines • 2.15 kB
JavaScript
import { WithClause } from "../models/Clause";
import { TokenType } from "../models/Lexeme";
import { SqlTokenizer } from "./SqlTokenizer";
import { CommonTableParser } from "./CommonTableParser";
export class WithClauseParser {
// 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 WITH clause is complete but there are additional tokens.`);
}
return result.value;
}
// Parse from lexeme array (was: parse)
static parseFromLexeme(lexemes, index) {
let idx = index;
// Expect WITH keyword
if (idx < lexemes.length && lexemes[idx].value.toLowerCase() === "with") {
idx++;
}
else {
throw new Error(`Syntax error at position ${idx}: Expected WITH keyword.`);
}
// Check for RECURSIVE keyword
const recursive = idx < lexemes.length && lexemes[idx].value.toLowerCase() === "recursive";
if (recursive) {
idx++;
}
// Parse CTEs
const tables = [];
// Parse first CTE (required)
const firstCte = CommonTableParser.parseFromLexeme(lexemes, idx);
tables.push(firstCte.value);
idx = firstCte.newIndex;
// Parse additional CTEs (optional)
while (idx < lexemes.length && (lexemes[idx].type & TokenType.Comma)) {
idx++; // Skip comma
const cteResult = CommonTableParser.parseFromLexeme(lexemes, idx);
tables.push(cteResult.value);
idx = cteResult.newIndex;
}
// Create WITH clause
return {
value: new WithClause(recursive, tables),
newIndex: idx
};
}
}
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