rawsql-ts
Version:
[beta]High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.
43 lines • 2.09 kB
JavaScript
import { FromClause } from "../models/Clause";
import { SqlTokenizer } from "./SqlTokenizer";
import { JoinClauseParser } from "./JoinClauseParser";
import { SourceExpressionParser } from "./SourceExpressionParser";
export class FromClauseParser {
// 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 FROM 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 !== 'from') {
throw new Error(`Syntax error at position ${idx}: Expected 'FROM' keyword but found "${lexemes[idx].value}". FROM clauses must start with the FROM keyword.`);
}
idx++;
if (idx >= lexemes.length) {
throw new Error(`Syntax error: Unexpected end of input after 'FROM' keyword. The FROM clause requires a table reference.`);
}
// Parse the main source expression
const sourceExpression = SourceExpressionParser.parseFromLexeme(lexemes, idx);
idx = sourceExpression.newIndex;
const join = JoinClauseParser.tryParse(lexemes, idx);
idx = (join === null || join === void 0 ? void 0 : join.newIndex) || idx;
if (join !== null) {
const clause = new FromClause(sourceExpression.value, join.value);
return { value: clause, newIndex: idx };
}
else {
const clause = new FromClause(sourceExpression.value, null);
return { value: clause, newIndex: idx };
}
}
}
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