[PATCH 2 of 5 V2] match: add option to return line and lineno from readpattern

[Laurent Charignon]

# HG changeset patch
# User Laurent Charignon <lcharignon at fb.com>
# Date 1451187638 28800
#      Sat Dec 26 19:40:38 2015 -0800
# Node ID 6b3004e5fd2b94fbe2397263465ab8d3acf683d1
# Parent  327bb58234a16dacf42ea57ff4dcb2c698f28638
match: add option to return line and lineno from readpattern

This will be used to display the line and linenumber of ignorefile that matched
an ignored file (issue4856).

diff --git a/mercurial/match.py b/mercurial/match.py
--- a/mercurial/match.py
+++ b/mercurial/match.py
@@ -632,7 +632,7 @@
 
 _commentre = None
 
-def readpatternfile(filepath, warn):
+def readpatternfile(filepath, warn, sourceinfo=False):
     '''parse a pattern file, returning a list of
     patterns. These patterns should be given to compile()
     to be validated and converted into a match function.
@@ -648,7 +648,11 @@
     syntax: glob   # defaults following lines to non-rooted globs
     re:pattern     # non-rooted regular expression
     glob:pattern   # non-rooted glob
-    pattern        # pattern of the current default type'''
+    pattern        # pattern of the current default type
+
+    if sourceinfo is set, returns a list of tuples:
+    (pattern, lineno, originalline). This is useful to debug ignore patterns.
+    '''
 
     syntaxes = {'re': 'relre:', 'regexp': 'relre:', 'glob': 'relglob:',
                 'include': 'include', 'subinclude': 'subinclude'}
@@ -656,7 +660,7 @@
     patterns = []
 
     fp = open(filepath)
-    for line in fp:
+    for lineno, line in enumerate(fp, start=1):
         if "#" in line:
             global _commentre
             if not _commentre:
@@ -691,6 +695,9 @@
                 linesyntax = rels
                 line = line[len(s) + 1:]
                 break
-        patterns.append(linesyntax + line)
+        if sourceinfo:
+            patterns.append((linesyntax + line, lineno, line))
+        else:
+            patterns.append(linesyntax + line)
     fp.close()
     return patterns