Class Parser

packages/core/src/constraints/parser.ts:78–419

}

class Parser {
  readonly source: string;
  private pos = 0;

  constructor(source: string) {
    this.source = source;
  }

  parse(): ExprNode {
    this.skipWhitespace();
    if (this.isEof()) {
      this.fail("Unexpected end of input");
    }
    const node = this.parseExpr();
    this.skipWhitespace();
    if (!this.isEof()) {
      const tok = this.peek();
      this.fail(tok === null ? "Unexpected end of input" : `Unexpected token "${tok}"`);
    }
    return node;
  }

  private parseExpr(): ExprNode {
    return this.parseTernary();
  }

  private parseTernary(): ExprNode {
    const condition = this.parseCompare();
    this.skipWhitespace();
    if (!this.consumeIf("?")) return condition;
    const thenExpr = this.parseExpr();
    this.skipWhitespace();
    if (!this.consumeIf(":")) {
      this.fail('Expected ":" in ternary expression');
    }
    const elseExpr = this.parseExpr();
    return {
      kind: "ternary",
      condition,
      // biome-ignore lint/suspicious/noThenProperty: "then" is an AST field (not a Promise-like thenable).
      then: thenExpr,
      else: elseExpr,
    };
  }

  private parseCompare(): ExprNode {
    const left = this.parseAdditive();
    this.skipWhitespace();
    const op = this.consumeCompareOp();
    if (op === null) return left;
    const right = this.parseAdditive();
    this.skipWhitespace();
    const extra = this.consumeCompareOp();
    if (extra !== null) {
      this.fail(
        "Only one comparison operator is allowed in a compare expression",
        this.pos - extra.length,
      );