templater: tokenize decimal integer literal (issue4638) (BC)

templater: tokenize decimal integer literal (issue4638) (BC)

Before this patch, we had to quote integer literals to pass to template
functions. It was error-prone, so we should allow "word(0, x)" syntax.
Currently only decimal integers are allowed. It's easy to support 0x, 0b and 0
prefixes, but I don't think they are useful.

This patch assumes that template keywords and names defined in map files do
not start with digits, except for positional variables seen in the schemes
extension.

--- a/mercurial/templater.py	Sat May 02 18:05:04 2015 +0900
+++ b/mercurial/templater.py	Fri May 01 20:43:55 2015 +0900
@@ -20,6 +20,7 @@
     "|": (5, None, ("|", 5)),
     "%": (6, None, ("%", 6)),
     ")": (0, None, None),
+    "integer": (0, ("integer",), None),
     "symbol": (0, ("symbol",), None),
     "string": (0, ("string",), None),
     "rawstring": (0, ("rawstring",), None),
@@ -59,6 +60,20 @@
                 pos += 1
             else:
                 raise error.ParseError(_("unterminated string"), s)
+        elif c.isdigit() or c == '-':
+            s = pos
+            if c == '-': # simply take negate operator as part of integer
+                pos += 1
+            if pos >= end or not program[pos].isdigit():
+                raise error.ParseError(_("integer literal without digits"), s)
+            pos += 1
+            while pos < end:
+                d = program[pos]
+                if not d.isdigit():
+                    break
+                pos += 1
+            yield ('integer', program[s:pos], s)
+            pos -= 1
         elif c.isalnum() or c in '_':
             s = pos
             pos += 1
@@ -135,6 +150,9 @@
         return context._load(exp[1])
     raise error.ParseError(_("expected template specifier"))
 
+def runinteger(context, mapping, data):
+    return int(data)
+
 def runstring(context, mapping, data):
     return data.decode("string-escape")
 
@@ -567,6 +585,7 @@
 
 # methods to interpret function arguments or inner expressions (e.g. {_(x)})
 exprmethods = {
+    "integer": lambda e, c: (runinteger, e[1]),
     "string": lambda e, c: (runstring, e[1]),
     "rawstring": lambda e, c: (runrawstring, e[1]),
     "symbol": lambda e, c: (runsymbol, e[1]),
@@ -579,6 +598,7 @@
 
 # methods to interpret top-level template (e.g. {x}, {x|_}, {x % "y"})
 methods = exprmethods.copy()
+methods["integer"] = exprmethods["symbol"]  # '{1}' as variable
 
 funcs = {
     "date": date,

--- a/tests/test-command-template.t	Sat May 02 18:05:04 2015 +0900
+++ b/tests/test-command-template.t	Fri May 01 20:43:55 2015 +0900
@@ -2291,6 +2291,39 @@
   hg: parse error: date expects a date information
   [255]
 
+Test integer literal:
+
+  $ hg log -Ra -r0 -T '{(0)}\n'
+  0
+  $ hg log -Ra -r0 -T '{(123)}\n'
+  123
+  $ hg log -Ra -r0 -T '{(-4)}\n'
+  -4
+  $ hg log -Ra -r0 -T '{(-)}\n'
+  hg: parse error at 2: integer literal without digits
+  [255]
+  $ hg log -Ra -r0 -T '{(-a)}\n'
+  hg: parse error at 2: integer literal without digits
+  [255]
+
+top-level integer literal is interpreted as symbol (i.e. variable name):
+
+  $ hg log -Ra -r0 -T '{1}\n'
+  
+  $ hg log -Ra -r0 -T '{if("t", "{1}")}\n'
+  
+  $ hg log -Ra -r0 -T '{1|stringify}\n'
+  
+
+unless explicit symbol is expected:
+
+  $ hg log -Ra -r0 -T '{desc|1}\n'
+  hg: parse error: expected a symbol, got 'integer'
+  [255]
+  $ hg log -Ra -r0 -T '{1()}\n'
+  hg: parse error: expected a symbol, got 'integer'
+  [255]
+
 Test string escaping:
 
   $ hg log -R latesttag -r 0 --template '>\n<>\\n<{if(rev, "[>\n<>\\n<]")}>\n<>\\n<\n'
@@ -2737,8 +2770,13 @@
   hg: parse error: word expects two or three arguments, got 7
   [255]
 
+Test word for integer literal
+
+  $ hg log -R a --template "{word(2, desc)}\n" -r0
+  line
+
 Test word for invalid numbers
 
-  $ hg log -Gv -R a --template "{word(2, desc)}"
+  $ hg log -Gv -R a --template "{word('a', desc)}"
   hg: parse error: Use strings like '3' for numbers passed to word function
   [255]