;;; nxml-util.el --- utility functions for nxml-*.el  -*- lexical-binding:t -*-

;; Copyright (C) 2003, 2007-2023 Free Software Foundation, Inc.

;; Author: James Clark
;; Keywords: wp, hypermedia, languages, XML

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(defconst nxml-debug nil
  "Enable nxml debugging.  Effective only at compile time.")

(defsubst nxml-debug (format &rest args)
  (when nxml-debug
    (apply #'message format args)))

(defmacro nxml-debug-change (name start end)
  (when nxml-debug
    `(nxml-debug "%s: %S" ,name
                (buffer-substring-no-properties ,start ,end))))

(defun nxml-make-namespace (str)
  "Return a symbol for the namespace URI STR.
STR must be a string.  If STR is the empty string, return nil.
Otherwise, return the symbol whose name is STR prefixed with a colon."
  (if (string-equal str "")
      nil
    (intern (concat ":" str))))

(defun nxml-namespace-name (ns)
  "Return the namespace URI corresponding to the symbol NS.
This is the inverse of `nxml-make-namespace'."
  (and ns (substring (symbol-name ns) 1)))

(defconst nxml-xml-namespace-uri
  (nxml-make-namespace "http://www.w3.org/XML/1998/namespace"))

(defconst nxml-xmlns-namespace-uri
  (nxml-make-namespace "http://www.w3.org/2000/xmlns/"))

(defmacro nxml-with-degradation-on-error (context &rest body)
  (declare (indent 1) (debug t))
  (if (not nxml-debug)
      (let ((error-symbol (make-symbol "err")))
        `(condition-case ,error-symbol
             (progn ,@body)
           (error
            (nxml-degrade ,context ,error-symbol))))
    `(progn ,@body)))

(defun nxml-display-file-parse-error (err)
  (let* ((filename (nth 1 err))
	 (buffer (find-file-noselect filename))
	 (pos (nth 2 err))
	 (message (nth 3 err)))
    (pop-to-buffer buffer)
    ;; What's the right thing to do if the buffer's modified?
    ;; The position in the saved file could be completely different.
    (goto-char (if (buffer-modified-p) 1 pos))
    (error "%s" message)))

(defun nxml-signal-file-parse-error (file pos message &optional error-symbol)
  (signal (or error-symbol 'nxml-file-parse-error)
	  (list file pos message)))

(define-error 'nxml-error nil)
(define-error 'nxml-file-parse-error "Error parsing file" 'nxml-error)

(provide 'nxml-util)

;;; nxml-util.el ends here
