rawsql-ts
Version:
[beta]High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.
40 lines • 2.04 kB
JavaScript
import { TokenType } from "../models/Lexeme";
import { IdentifierString } from "../models/ValueComponent";
import { SqlTokenizer } from "./SqlTokenizer";
import { WindowExpressionParser } from "./WindowExpressionParser";
export class OverExpressionParser {
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 OVER expression is complete but there are additional tokens.`);
}
return result.value;
}
static parseFromLexeme(lexemes, index) {
let idx = index;
if (lexemes[idx].value !== 'over') {
throw new Error(`Syntax error at position ${idx}: Expected 'OVER' keyword but found "${lexemes[idx].value}". OVER expressions must start with the OVER keyword.`);
}
idx++;
if (idx >= lexemes.length) {
throw new Error(`Syntax error: Unexpected end of input after 'OVER' keyword. Expected either a window name or an opening parenthesis '('.`);
}
if (lexemes[idx].type & TokenType.Identifier) {
// named window frame
const name = lexemes[idx].value;
idx++;
return { value: new IdentifierString(name), newIndex: idx };
}
if (lexemes[idx].type & TokenType.OpenParen) {
// Delegate processing to WindowFrameExpressionParser
const result = WindowExpressionParser.parseFromLexeme(lexemes, idx);
return result;
}
throw new Error(`Syntax error at position ${idx}: Expected a window name or opening parenthesis '(' after OVER keyword, but found "${lexemes[idx].value}".`);
}
}
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