Method #emitDeclaration

xml/_tokenizer.ts:718–762

(target: string, content: string)

  }

  #emitDeclaration(target: string, content: string): void {
    // XML 1.0 §2.6: Only exact lowercase "xml" is valid for XML declaration
    // Case variants like "XML", "xMl" are reserved and invalid
    if (target !== "xml") {
      this.#error(
        `Processing instruction target '${target}' is reserved; 'xml' must be lowercase (XML 1.0 §2.6)`,
      );
    }

    // XML 1.0 §2.8: XML declaration must be at the very beginning
    // (only a UTF BOM may precede it)
    // Check both: no content has been emitted, AND if position tracking is on,
    // verify the offset is correct (handles BOM case)
    if (!this.#xmlDeclAllowed) {
      this.#error(
        "XML declaration must appear at the start of the document (XML 1.0 §2.8)",
      );
    }
    // If position tracking is enabled, also verify exact offset
    if (this.#trackPosition) {
      const allowedOffset = this.#firstCharWasBOM ? 1 : 0;
      if (this.#tokenOffset !== allowedOffset) {
        this.#error(
          "XML declaration must appear at the start of the document (XML 1.0 §2.8)",
        );
      }
    }
    // After emitting declaration, no more XMLDecl is allowed
    this.#xmlDeclAllowed = false;

    // Validate XML declaration syntax strictly
    const result = validateXmlDeclaration(content);
    if (!result.valid) {
      this.#error(result.error);
    }

    this.#callbacks.onDeclaration?.(
      result.version,
      result.encoding,
      result.standalone,
      this.#tokenLine,
      this.#tokenColumn,
      this.#tokenOffset,
    );
  }

  /** Read a quoted string in DOCTYPE. Does not handle cross-chunk boundaries. */
  #readDoctypeQuotedString(): string {