Check for missing or duplicated anchors

docs/rules.rst

@@ -14,6 +14,11 @@ This page describes the rules and their options.
    :local:
    :depth: 1
 
+anchors
+-------
+
+.. automodule:: yamllint.rules.anchors
+
 braces
 ------
 

tests/rules/test_anchors.py

@@ -0,0 +1,117 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2021 Sergei Mikhailov
+#
+# 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/>.
+
+from tests.common import RuleTestCase
+
+
+HIT_ANCHOR_POINTER = '''---
+key: &keyanchor a
+otherkey: *keyanchor
+'''
+MISS_ANCHOR_POINTER = '''---
+key: &keyanchor a
+otherkey: *missedkeyanchor
+'''
+
+HIT_ANCHOR_MERGE = '''---
+block: &keyanchor
+  key: a
+otherkey:
+  <<: *keyanchor
+  otherkey: b
+'''
+MISS_ANCHOR_MERGE = '''---
+block: &keyanchor
+  key: a
+otherkey:
+  <<: *missedkeyanchor
+  otherkey: b
+'''
+
+MULTI_HIT_ANCHOR_POINTER = '''---
+key: &keyanchor a
+otherkey: *keyanchor
+otherotherkey: *keyanchor
+'''
+MULTI_MISS_ANCHOR_POINTER = '''---
+key: &keyanchor a
+otherkey: *missedkeyanchor
+otherotherkey: *missedkeyanchor
+'''
+
+MULTI_DOC_HIT_ANCHOR_POINTER = '''---
+key: &keyanchor a
+otherkey: *keyanchor
+---
+key: &otherkeyanchor a
+otherkey: *otherkeyanchor
+'''
+MULTI_DOC_MISS_ANCHOR_POINTER = '''---
+key: &keyanchor a
+otherkey: *missedkeyanchor
+---
+key: &otherkeyanchor a
+otherkey: *othermissedkeyanchor
+'''
+
+DUPLICATE_ANCHORS = '''---
+first_block: &keyanchor
+  key: a
+
+second_block: &keyanchor
+  key: b
+
+target_block: *keyanchor
+'''
+
+
+class AnchorsTestCase(RuleTestCase):
+    rule_id = 'anchors'
+
+    def test_disabled(self):
+        conf = 'anchors: disable'
+
+        self.check(HIT_ANCHOR_POINTER, conf)
+        self.check(HIT_ANCHOR_MERGE, conf)
+        self.check(MULTI_HIT_ANCHOR_POINTER, conf)
+        self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
+
+        self.check(MISS_ANCHOR_POINTER, conf)
+        self.check(MISS_ANCHOR_MERGE, conf)
+        self.check(MULTI_MISS_ANCHOR_POINTER, conf)
+        self.check(MULTI_DOC_MISS_ANCHOR_POINTER, conf)
+        self.check(DUPLICATE_ANCHORS, conf)
+
+    def test_enabled(self):
+        conf = 'anchors: enable'
+
+        self.check(HIT_ANCHOR_POINTER, conf)
+        self.check(HIT_ANCHOR_MERGE, conf)
+        self.check(MULTI_HIT_ANCHOR_POINTER, conf)
+        self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
+
+        self.check(MISS_ANCHOR_POINTER, conf,
+                   problem=(3, 11))
+        self.check(MISS_ANCHOR_MERGE, conf,
+                   problem_first=(5, 7),
+                   problem_second=(5, 7))
+        self.check(MULTI_MISS_ANCHOR_POINTER, conf,
+                   problem_first=(3, 11),
+                   problem_second=(4, 16))
+        self.check(MULTI_DOC_MISS_ANCHOR_POINTER, conf,
+                   problem_first=(3, 11), problem_second=(6, 11))
+        self.check(DUPLICATE_ANCHORS, conf,
+                   problem=(5, 15))

yamllint/conf/default.yaml

@@ -6,6 +6,7 @@ yaml-files:
   - '.yamllint'
 
 rules:
+  anchors: enable
   braces: enable
   brackets: enable
   colons: enable

yamllint/rules/__init__.py

@@ -14,6 +14,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from yamllint.rules import (
+    anchors,
     braces,
     brackets,
     colons,
@@ -39,6 +40,7 @@ from yamllint.rules import (
 )
 
 _RULES = {
+    anchors.ID: anchors,
     braces.ID: braces,
     brackets.ID: brackets,
     colons.ID: colons,

yamllint/rules/anchors.py

@@ -0,0 +1,117 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2021 Sergei Mikhailov
+#
+# 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 aliases pointing to pointers that don't exist.
+
+.. rubric:: Examples
+
+#. With ``anchors: {}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    address: &address |
+      Williams St. 13
+    target_address: *address
+
+   the following code snippet would **FAIL**:
+   ::
+
+    address: &address |
+      Williams St. 13
+    target_address: *wrong_address
+
+#. This appends to merges as well:
+
+   the following code snippet would **PASS**:
+   ::
+
+    default_address: &address
+      state: South Carolina
+      city:  Barnwell
+    target_address:
+      <<: *address
+      city: Barnaul
+
+   the following code snippet would **FAIL**:
+   ::
+
+    default_address: &address
+      state: South Carolina
+      city:  Barnwell
+    target_address:
+      <<: *wrong_address
+      city: Barnaul
+
+#. Duplicate anchors are not allowed.
+
+   the following code snippet would **PASS**:
+   ::
+
+    clients:
+        jack: &jack_client
+            billing_id: 1234
+        bill: &bill_client
+            billing_id: 5678
+    target_client: *jack_client
+
+   the following code snippet would **FAIL**:
+   ::
+
+    clients:
+        jack: &jack_client
+            billing_id: 1234
+        bill: &jack_client
+            billing_id: 5678
+    target_client: *jack_client
+"""
+
+from yaml import DocumentStartToken, AnchorToken, AliasToken, BlockEndToken
+
+from yamllint.linter import LintProblem
+
+
+ID = 'anchors'
+TYPE = 'token'
+
+
+def check(__conf, token, __prev, __next, __nextnext, context):
+    if isinstance(token, (DocumentStartToken)):
+        context['anchors'] = set()
+        context['aliases'] = {}
+    elif ('anchors' in context and 'aliases' in context):
+        if isinstance(token, (AnchorToken)):
+            if token.value in context['anchors']:
+                yield LintProblem(
+                    token.start_mark.line + 1, token.start_mark.column + 1,
+                    f"anchor '{token.value}' duplicates in document")
+            context['anchors'].add(token.value)
+        elif isinstance(token, (AliasToken)):
+            if token.value not in context['aliases']:
+                context['aliases'][token.value] = []
+            alias_obj = {"line": token.start_mark.line,
+                         "column": token.start_mark.column}
+            context['aliases'][token.value].append(alias_obj)
+        elif isinstance(token, (BlockEndToken)):
+            missing_anchors = [alias for alias in list(context['aliases'])
+                               if alias not in context['anchors']]
+            if len(missing_anchors) > 0:
+                for miss_anchor in missing_anchors:
+                    for location in context['aliases'][miss_anchor]:
+                        yield LintProblem(
+                            location['line'] + 1, location['column'] + 1,
+                            f"anchor '{miss_anchor}' is not found in document")