templater: introduce startswith function
This function returns a string only if it starts with a given string.
It is particularly useful when combined with splitlines and/or used with
conditionals that fail when empty strings are passed in to take action
based on the contents of a line.
--- a/mercurial/help/templates.txt Thu Jun 12 17:45:41 2014 -0700
+++ b/mercurial/help/templates.txt Thu Jun 12 17:53:37 2014 -0700
@@ -66,6 +66,8 @@
- shortest(node)
+- startswith(string, text)
+
- strip(text[, chars])
- sub(pat, repl, expr)
@@ -124,3 +126,7 @@
- Mark the working copy parent with '@'::
$ hg log --template "{ifcontains(rev, revset('.'), '@')}\n"
+
+- Show only commit descriptions that start with "template"::
+
+ $ hg log --template "{startswith(\"template\", firstline(desc))}\n"
--- a/mercurial/templater.py Thu Jun 12 17:45:41 2014 -0700
+++ b/mercurial/templater.py Thu Jun 12 17:53:37 2014 -0700
@@ -466,6 +466,17 @@
src = stringify(_evalifliteral(args[2], context, mapping))
yield re.sub(pat, rpl, src)
+def startswith(context, mapping, args):
+ if len(args) != 2:
+ raise error.ParseError(_("startswith expects two arguments"))
+
+ patn = stringify(args[0][0](context, mapping, args[0][1]))
+ text = stringify(args[1][0](context, mapping, args[1][1]))
+ if text.startswith(patn):
+ return text
+ return ''
+
+
methods = {
"string": lambda e, c: (runstring, e[1]),
"rawstring": lambda e, c: (runrawstring, e[1]),
@@ -490,6 +501,7 @@
"revset": revset,
"rstdoc": rstdoc,
"shortest": shortest,
+ "startswith": startswith,
"strip": strip,
"sub": sub,
}
--- a/tests/test-command-template.t Thu Jun 12 17:45:41 2014 -0700
+++ b/tests/test-command-template.t Thu Jun 12 17:53:37 2014 -0700
@@ -1884,3 +1884,30 @@
| foo other 3
o foo line 1
foo line 2
+
+Test startswith
+ $ hg log -Gv -R a --template "{startswith(desc)}"
+ hg: parse error: startswith expects two arguments
+ [255]
+
+ $ hg log -Gv -R a --template "{startswith('line', desc)}"
+ @
+ |
+ o
+ |
+ o
+
+ o
+ |\
+ | o
+ | |
+ o |
+ |/
+ o
+ |
+ o
+ |
+ o
+ |
+ o line 1
+ line 2