Feature: checking octal numbers

yamllint/conf/default.yaml

@@ -50,6 +50,9 @@ rules:
   new-line-at-end-of-file: enable
   new-lines:
     type: unix
+  octal-values:
+    forbid-implicit-octal: false
+    forbid-explicit-octal: false
   trailing-spaces: enable
   truthy:
     level: warning

yamllint/rules/__init__.py

@@ -32,6 +32,7 @@ from yamllint.rules import (
     line_length,
     new_line_at_end_of_file,
     new_lines,
+    octal_values,
     trailing_spaces,
     truthy,
 )
@@ -54,6 +55,7 @@ _RULES = {
     line_length.ID: line_length,
     new_line_at_end_of_file.ID: new_line_at_end_of_file,
     new_lines.ID: new_lines,
+    octal_values.ID: octal_values,
     trailing_spaces.ID: trailing_spaces,
     truthy.ID: truthy,
 }

yamllint/rules/octal_values.py

@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2017 ScienJus
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Use this rule to prevent values with octal numbers. In YAML, numbers that
+start with ``0`` are interpreted as octal, but this is not always wanted.
+For instance ``010`` is the city code of Beijing, and should not be
+converted to ``8``.
+
+.. rubric:: Examples
+
+#. With ``octal-values: {forbid-implicit-octal: true}``
+
+   the following code snippets would **PASS**:
+   ::
+
+    user:
+      city-code: '010'
+
+   the following code snippets would **PASS**:
+   ::
+
+    user:
+      city-code: 010,021
+
+   the following code snippets would **FAIL**:
+   ::
+
+    user:
+      city-code: 010
+
+#. With ``octal-values: {forbid-explicit-octal: true}``
+
+   the following code snippets would **PASS**:
+   ::
+
+    user:
+      city-code: '0o10'
+
+   the following code snippets would **FAIL**:
+   ::
+
+    user:
+      city-code: 0o10
+"""
+
+import yaml
+
+from yamllint.linter import LintProblem
+
+
+ID = 'octal-values'
+TYPE = 'token'
+CONF = {'forbid-implicit-octal': bool,
+        'forbid-explicit-octal': bool}
+
+
+def check(conf, token, prev, next, nextnext, context):
+    if prev and isinstance(prev, yaml.tokens.TagToken):
+        return
+
+    if conf['forbid-implicit-octal']:
+        if isinstance(token, yaml.tokens.ScalarToken):
+            if not token.style:
+                val = token.value
+                if val.isdigit() and len(val) > 1 and val[0] == '0':
+                    yield LintProblem(
+                        token.start_mark.line + 1, token.end_mark.column + 1,
+                        'forbidden implicit octal value "%s"' %
+                        token.value)
+
+    if conf['forbid-explicit-octal']:
+        if isinstance(token, yaml.tokens.ScalarToken):
+            if not token.style:
+                val = token.value
+                if len(val) > 2 and val[:2] == '0o' and val[2:].isdigit():
+                    yield LintProblem(
+                        token.start_mark.line + 1, token.end_mark.column + 1,
+                        'forbidden explicit octal value "%s"' %
+                        token.value)