rawsql-ts
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High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.
47 lines • 2.48 kB
JavaScript
import { WhereClause } from "../models/Clause";
import { SqlTokenizer } from "./SqlTokenizer";
import { ValueParser } from "./ValueParser";
import { CommentUtils } from "../utils/CommentUtils";
export class WhereClauseParser {
// 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 WHERE clause is complete but there are additional tokens.`);
}
return result.value;
}
// Parse from lexeme array (was: parse)
static parseFromLexeme(lexemes, index) {
let idx = index;
// Capture comments associated with the WHERE clause
const whereLexeme = lexemes[idx];
const whereTokenComments = CommentUtils.collectClauseComments(lexemes, idx, 'where');
// Preserve positioned comments from the WHERE keyword so we can reapply them during printing
const wherePositionedComments = whereLexeme.positionedComments;
if (whereLexeme.value !== 'where') {
throw new Error(`Syntax error at position ${idx}: Expected 'WHERE' keyword but found "${lexemes[idx].value}". WHERE clauses must start with the WHERE keyword.`);
}
idx++;
if (idx >= lexemes.length) {
throw new Error(`Syntax error: Unexpected end of input after 'WHERE' keyword. The WHERE clause requires a condition expression.`);
}
const item = ValueParser.parseFromLexeme(lexemes, idx);
const clause = new WhereClause(item.value);
// Set comments from the WHERE token to the clause
clause.comments = whereTokenComments;
if (wherePositionedComments && wherePositionedComments.length > 0) {
// Clone positioned comments so mutations on the clause do not leak back to the tokenizer state
clause.positionedComments = wherePositionedComments.map((comment) => ({
position: comment.position,
comments: [...comment.comments],
}));
}
return { value: clause, newIndex: item.newIndex };
}
}
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