Perform xref searches without visiting unopened files

* lisp/progmodes/xref.el (xref-collect-references): Instead of
calling `semantic-symref-find-references-by-name', use
`semantic-symref-instantiate' and `semantic-symref-perform-search'
directly.  Ask for `line-and-text' results (bug#23223).
(xref-collect-matches): Include the line text in the "hit"
structure.
(xref--convert-hits): New function, split off from
`xref-collect-references' and `xref-collect-matches', to convert
"hits" to xref instance list.  Create a temporary buffer here, to
use it for post-processing all hit lines.
(xref--collect-matches): Use a different approach for non-visited
files.  Insert the line text into the temp buffer, apply the
file's major mode the best we can without reading its whole
contents, syntax-propertize, and search in the result.
(xref--collect-matches-1): Extract, to handle the common logic
between two cases.
(xref--find-buffer-visiting): New function, a wrapper around
`find-buffer-visiting' to amortize its cost.

* lisp/cedet/semantic/symref/idutils.el
(semantic-symref-idutils--line-re): New constant.
(semantic-symref-parse-tool-output-one-line): Support result type
`line-and-text'.

* lisp/cedet/semantic/symref/grep.el
(semantic-symref-grep--line-re)
(semantic-symref-parse-tool-output-one-line): Same.

* lisp/cedet/semantic/symref/cscope.el
(semantic-symref-cscope--line-re)
(semantic-symref-parse-tool-output-one-line): Same.

* lisp/cedet/semantic/symref/global.el
(semantic-symref-global--line-re)
(semantic-symref-parse-tool-output-one-line): Same.

4 files changed, 38 insertions, 6 deletions

diff --git a/lisp/cedet/semantic/symref/cscope.el b/lisp/cedet/semantic/symref/cscope.el
index 4890b5b5755..3abd8b3f51c 100644
--- a/lisp/cedet/semantic/symref/cscope.el
+++ b/lisp/cedet/semantic/symref/cscope.el
@@ -60,6 +60,9 @@ See the function `cedet-cscope-search' for more details.")
     (semantic-symref-parse-tool-output tool b)
     ))
 
+(defconst semantic-symref-cscope--line-re
+  "^\\([^ ]+\\) [^ ]+ \\([0-9]+\\) ")
+
 (cl-defmethod semantic-symref-parse-tool-output-one-line ((tool semantic-symref-tool-cscope))
   "Parse one line of grep output, and return it as a match list.
 Moves cursor to end of the match."
@@ -78,8 +81,13 @@ Moves cursor to end of the match."
 	       ;; We have to return something at this point.
 	       subtxt)))
 	 )
-	(t
-	 (when (re-search-forward "^\\([^ ]+\\) [^ ]+ \\([0-9]+\\) " nil t)
+        ((eq (oref tool :resulttype) 'line-and-text)
+         (when (re-search-forward semantic-symref-cscope--line-re nil t)
+           (list (string-to-number (match-string 2))
+                 (expand-file-name (match-string 1))
+                 (buffer-substring-no-properties (point) (line-end-position)))))
+	(t ; :resulttype is 'line
+	 (when (re-search-forward semantic-symref-cscope--line-re nil t)
 	   (cons (string-to-number (match-string 2))
 		 (expand-file-name (match-string 1)))
 	   ))))
diff --git a/lisp/cedet/semantic/symref/global.el b/lisp/cedet/semantic/symref/global.el
index e4c114e9c89..a33427e93a6 100644
--- a/lisp/cedet/semantic/symref/global.el
+++ b/lisp/cedet/semantic/symref/global.el
@@ -49,6 +49,9 @@ See the function `cedet-gnu-global-search' for more details.")
     (semantic-symref-parse-tool-output tool b)
     ))
 
+(defconst semantic-symref-global--line-re
+  "^\\([^ ]+\\) +\\([0-9]+\\) \\([^ ]+\\) ")
+
 (cl-defmethod semantic-symref-parse-tool-output-one-line ((tool semantic-symref-tool-global))
   "Parse one line of grep output, and return it as a match list.
 Moves cursor to end of the match."
@@ -57,8 +60,13 @@ Moves cursor to end of the match."
 	 ;; Search for files
 	 (when (re-search-forward "^\\([^\n]+\\)$" nil t)
 	   (match-string 1)))
+        ((eq (oref tool :resulttype) 'line-and-text)
+         (when (re-search-forward semantic-symref-global--line-re nil t)
+           (list (string-to-number (match-string 2))
+                 (match-string 3)
+                 (buffer-substring-no-properties (point) (line-end-position)))))
 	(t
-	 (when (re-search-forward "^\\([^ ]+\\) +\\([0-9]+\\) \\([^ ]+\\) " nil t)
+	 (when (re-search-forward semantic-symref-global--line-re nil t)
 	   (cons (string-to-number (match-string 2))
 		 (match-string 3))
 	   ))))
diff --git a/lisp/cedet/semantic/symref/grep.el b/lisp/cedet/semantic/symref/grep.el
index 5d1fea8c829..868e6c3f726 100644
--- a/lisp/cedet/semantic/symref/grep.el
+++ b/lisp/cedet/semantic/symref/grep.el
@@ -188,6 +188,9 @@ This shell should support pipe redirect syntax."
     ;; Return the answer
     ans))
 
+(defconst semantic-symref-grep--line-re
+  "^\\(\\(?:[a-zA-Z]:\\)?[^:\n]+\\):\\([0-9]+\\):")
+
 (cl-defmethod semantic-symref-parse-tool-output-one-line ((tool semantic-symref-tool-grep))
   "Parse one line of grep output, and return it as a match list.
 Moves cursor to end of the match."
@@ -195,8 +198,13 @@ Moves cursor to end of the match."
 	 ;; Search for files
 	 (when (re-search-forward "^\\([^\n]+\\)$" nil t)
 	   (match-string 1)))
+        ((eq (oref tool :resulttype) 'line-and-text)
+         (when (re-search-forward semantic-symref-grep--line-re nil t)
+           (list (string-to-number (match-string 2))
+                 (match-string 1)
+                 (buffer-substring-no-properties (point) (line-end-position)))))
 	(t
-	 (when (re-search-forward  "^\\(\\(?:[a-zA-Z]:\\)?[^:\n]+\\):\\([0-9]+\\):" nil t)
+	 (when (re-search-forward semantic-symref-grep--line-re nil t)
 	   (cons (string-to-number (match-string 2))
 		 (match-string 1))
 	   ))))
diff --git a/lisp/cedet/semantic/symref/idutils.el b/lisp/cedet/semantic/symref/idutils.el
index 4127d7ae4ea..db3e9a0dddb 100644
--- a/lisp/cedet/semantic/symref/idutils.el
+++ b/lisp/cedet/semantic/symref/idutils.el
@@ -49,6 +49,9 @@ See the function `cedet-idutils-search' for more details.")
     (semantic-symref-parse-tool-output tool b)
     ))
 
+(defconst semantic-symref-idutils--line-re
+  "^\\(\\(?:[a-zA-Z]:\\)?[^:\n]+\\):\\([0-9]+\\):")
+
 (cl-defmethod semantic-symref-parse-tool-output-one-line ((tool semantic-symref-tool-idutils))
   "Parse one line of grep output, and return it as a match list.
 Moves cursor to end of the match."
@@ -59,8 +62,13 @@ Moves cursor to end of the match."
 	((eq (oref tool :searchtype) 'tagcompletions)
 	 (when (re-search-forward "^\\([^ ]+\\) " nil t)
 	   (match-string 1)))
-	(t
-	 (when (re-search-forward "^\\(\\(?:[a-zA-Z]:\\)?[^:\n]+\\):\\([0-9]+\\):" nil t)
+        ((eq (oref tool :resulttype) 'line-and-text)
+         (when (re-search-forward semantic-symref-idutils--line-re nil t)
+	   (list (string-to-number (match-string 2))
+                 (expand-file-name (match-string 1) default-directory)
+                 (buffer-substring-no-properties (point) (line-end-position)))))
+	(t ; resulttype is line
+	 (when (re-search-forward semantic-symref-idutils--line-re nil t)
 	   (cons (string-to-number (match-string 2))
 		 (expand-file-name (match-string 1) default-directory))
 	   ))))