From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Tue, 18 Jun 2024 22:16:10 +0000 (-0400)
Subject: editorconfig-core-handle.el: Reduce allocation in parser
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=57706ea1f15ab1576090956975df141229aad17b;p=emacs.git

editorconfig-core-handle.el: Reduce allocation in parser

* lisp/editorconfig-core-handle.el (editorconfig-core-handle--parse-file):
Return a `editorconfig-core-handle`.
(editorconfig-core-handle): Simplify accordingly.
(editorconfig-core-handle--parse-file): Push `sections` and `props`
in reverse order to avoid the usual O(N²) complexity.
Work directly in the buffer instead of extracting "lines" from it, so
as to reduce memory allocation.  Similarly, use careful regexps so we
can extract trimmed strings without an explicit trim operation.
Use `eobp`.
(editorconfig-core-handle--string-trim): Delete function, not used any more.

(cherry picked from commit 833b500a0e788a95c189a5b2bfa95494a3a7429e)
---

diff --git a/lisp/editorconfig-core-handle.el b/lisp/editorconfig-core-handle.el
index 38353b7deb7..8857c35c62c 100644
--- a/lisp/editorconfig-core-handle.el
+++ b/lisp/editorconfig-core-handle.el
@@ -93,12 +93,7 @@ If CONF does not exist return nil."
                (equal (editorconfig-core-handle-mtime cached) mtime))
           cached
         (let ((parsed (editorconfig-core-handle--parse-file conf)))
-          (puthash conf
-                   (make-editorconfig-core-handle :top-props (plist-get parsed :top-props)
-                                                  :sections (plist-get parsed :sections)
-                                                  :mtime mtime
-                                                  :path conf)
-                   editorconfig-core-handle--cache-hash))))))
+          (puthash conf parsed editorconfig-core-handle--cache-hash))))))
 
 (defun editorconfig-core-handle-root-p (handle)
   "Return non-nil if HANDLE represent root EditorConfig file.
@@ -148,21 +143,10 @@ This function is a fnmatch with a few modification for EditorConfig usage."
         (editorconfig-fnmatch-p name pattern))
     (editorconfig-fnmatch-p (file-name-nondirectory name) pattern)))
 
-(defsubst editorconfig-core-handle--string-trim (str)
-  "Remove leading and trailing whitespaces from STR."
-  (replace-regexp-in-string "[[:space:]]+\\'"
-                            ""
-                            (replace-regexp-in-string "\\`[[:space:]]+"
-                                                      ""
-                                                      str)))
-
 (defun editorconfig-core-handle--parse-file (conf)
   "Parse EditorConfig file CONF.
 
-This function returns cons of its top properties alist and
-alist of patterns and its properties alist.
-The list returned will be ordered by the lines they appear.
-
+This function returns a `editorconfig-core-handle'.
 If CONF is not found return nil."
   (when (file-readable-p conf)
     (with-temp-buffer
@@ -170,12 +154,9 @@ If CONF is not found return nil."
       ;; code conversion
       (insert-file-contents conf)
       (goto-char (point-min))
-      (let ((point-max (point-max))
-            (sections ())
+      (let ((sections ())
             (top-props nil)
 
-            ;; String of current line
-            (line "")
             ;; nil when pattern not appeared yet, "" when pattern is empty ("[]")
             (pattern nil)
             ;; Alist of properties for current PATTERN
@@ -183,58 +164,52 @@ If CONF is not found return nil."
 
             ;; Current line num
             (current-line-number 1))
-        (while (not (eq (point) point-max))
-          (setq line
-                (buffer-substring-no-properties (line-beginning-position)
-                                                (line-end-position)))
-          (setq line
-                (replace-regexp-in-string "\\(^\\| \\)\\(#\\|;\\).*$"
-                                          ""
-                                          (editorconfig-core-handle--string-trim line)))
-
+        (while (not (eobp))
+          (skip-chars-forward " \t\f")
           (cond
-           ((string-equal "" line)
+           ((looking-at "\\(?:[#;].*\\)?$")
             nil)
 
            ;; Start of section
-           ((string-match "^\\[\\(.*\\)\\]$"
-                          line)
-            (when pattern
-              (setq sections
-                    `(,@sections ,(make-editorconfig-core-handle-section
-                                   :name pattern
-                                   :props props)))
-              (setq pattern nil)
-              (setq props nil))
-            (setq pattern (match-string 1 line)))
-
-           (t
-            (let ((idx (string-match "=\\|:" line)))
-              (unless idx
-                (error "Error while reading config file: %s:%d:\n    %s\n"
-                       conf current-line-number line))
-              (let ((key (downcase (editorconfig-core-handle--string-trim
-                                    (substring line 0 idx))))
-                    (value (editorconfig-core-handle--string-trim
-                            (substring line (1+ idx)))))
-                (when (and (< (length key) 51)
-                           (< (length value) 256))
-                  (if pattern
-                      (when (< (length pattern) 4097)
-                        (setq props
-                              `(,@props (,key . ,value))))
-                    (setq top-props
-                          `(,@top-props (,key . ,value)))))))))
+           ((looking-at "\\[\\(.*\\)\\][ \t]*$")
+            (let ((newpattern (match-string 1)))
+              (when pattern
+                (push (make-editorconfig-core-handle-section
+                       :name pattern
+                       :props (nreverse props))
+                      sections))
+              (setq props nil)
+              (setq pattern newpattern)))
+
+           ((looking-at "\\([^=: \t]+\\)[ \t]*[=:][ \t]*\\(.*?\\)[ \t]*$")
+            (let ((key (downcase (match-string 1)))
+                  (value (match-string 2)))
+              (when (and (< (length key) 51)
+                         (< (length value) 256))
+                (if pattern
+                    (when (< (length pattern) 4097) ;;FIXME: 4097?
+                      (push `(,key . ,value)
+                            props))
+                  (push `(,key . ,value)
+                        top-props)))))
+
+           (t (error "Error while reading config file: %s:%d:\n    %s\n"
+                     conf current-line-number
+                     (buffer-substring-no-properties (line-beginning-position)
+                                                     (line-end-position)))))
           (setq current-line-number (1+ current-line-number))
           (goto-char (point-min))
           (forward-line (1- current-line-number)))
         (when pattern
-          (setq sections
-                `(,@sections ,(make-editorconfig-core-handle-section
-                               :name pattern
-                               :props props))))
-        (list :top-props top-props
-              :sections sections)))))
+          (push (make-editorconfig-core-handle-section
+                 :name pattern
+                 :props (nreverse props))
+                sections))
+        (make-editorconfig-core-handle
+         :top-props (nreverse top-props)
+         :sections (nreverse sections)
+         :mtime (nth 5 (file-attributes conf))
+         :path conf)))))
 
 (provide 'editorconfig-core-handle)
 ;;; editorconfig-core-handle.el ends here