snapcraft/internal/project_loader/grammar/_processor.py

@@ -19,7 +19,7 @@
 from .errors import GrammarSyntaxError
 
 _ON_CLAUSE_PATTERN = re.compile(r'\Aon\s+')
-_TO_CLAUSE_PATTERN = re.compile(r'\Ato\s+')
+_TO_CLAUSE_PATTERN = re.compile(r'(\Aon\s+\S+\s+|)to\s+')
 _TRY_CLAUSE_PATTERN = re.compile(r'\Atry\Z')
 _ELSE_CLAUSE_PATTERN = re.compile(r'\Aelse\Z')
 _ELSE_FAIL_PATTERN = re.compile(r'\Aelse\s+fail\Z')
@@ -75,26 +75,26 @@ def _parse_dict(section, statement, statements, project_options,
     from ._try import TryStatement
 
     for key, value in section.items():
-        if _ON_CLAUSE_PATTERN.match(key):
-            # We've come across the beginning of an 'on' statement.
+        if _TO_CLAUSE_PATTERN.match(key):
+            # We've come across the beginning of a 'to' statement.
             # That means any previous statement we found is complete.
             # The first time through this may be None, but the
             # collection will ignore it.
             statements.add(statement)
 
-            statement = OnStatement(
-                on=key, body=value, project_options=project_options,
+            statement = ToStatement(
+                to=key, body=value, project_options=project_options,
                 checker=checker)
 
-        if _TO_CLAUSE_PATTERN.match(key):
-            # We've come across the beginning of a 'to' statement.
+        elif _ON_CLAUSE_PATTERN.match(key):
+            # We've come across the beginning of an 'on' statement.
             # That means any previous statement we found is complete.
             # The first time through this may be None, but the
             # collection will ignore it.
             statements.add(statement)
 
-            statement = ToStatement(
-                to=key, body=value, project_options=project_options,
+            statement = OnStatement(
+                on=key, body=value, project_options=project_options,
                 checker=checker)
 
         if _TRY_CLAUSE_PATTERN.match(key):

snapcraft/internal/project_loader/grammar/_to.py

@@ -16,13 +16,15 @@
 
 import re
 
+import snapcraft
 from . import process_grammar
 from .errors import (
     ToStatementSyntaxError,
     UnsatisfiedStatementError,
 )
 
-_SELECTOR_PATTERN = re.compile(r'\Ato\s+([^,\s](?:,?[^,]+)*)\Z')
+_SELECTOR_PATTERN = re.compile(
+    r'(\Aon\s+[^,\s](?:,?[^,]+)*\s|)to\s+([^,\s](?:,?[^,]+)*)\Z')
 _WHITESPACE_PATTERN = re.compile(r'\A.*\s.*\Z')
 
 
@@ -57,7 +59,7 @@ def __init__(self, *, to, body, project_options, checker):
         :type checker: callable
         """
 
-        self.selectors = _extract_to_clause_selectors(to)
+        self._on_selectors, self.selectors = _extract_to_clause_selectors(to)
         self._body = body
         self._project_options = project_options
         self._checker = checker
@@ -82,11 +84,17 @@ def process(self):
 
         primitives = set()
         target_arch = self._project_options.deb_arch
+        host_arch = snapcraft.ProjectOptions().deb_arch
 
         # The only selector currently supported is the target arch. Since
         # selectors are matched with an AND, not OR, there should only be one
         # selector.
-        if (len(self.selectors) == 1) and (target_arch in self.selectors):
+        on_matches = (((len(self._on_selectors) == 1) and
+                      host_arch in self._on_selectors) or
+                      self._on_selectors == {''})
+        to_matches = ((len(self.selectors) == 1) and
+                      (target_arch in self.selectors))
+        if on_matches and to_matches:
             primitives = process_grammar(
                 self._body, self._project_options, self._checker)
             # target arch is the default (not the host arch) in a to statement
@@ -123,18 +131,21 @@ def _extract_to_clause_selectors(to):
 
     :param str to: The 'to <selector>' part of the 'to' clause.
 
-    :return: Selectors found within the 'to' clause.
+    :return: Tuple of selectors found within a 'to' or 'on to' clause
     :rtype: set
 
     For example:
-    >>> _extract_to_clause_selectors('to amd64,i386') == {'amd64', 'i386'}
+    >>> _extract_to_clause_selectors('to amd64,i386') == ({''},{'amd64', 'i386'})
     True
-    """
+    >>> _extract_to_clause_selectors('on amd64 to i386') == ({'amd64'},{'i386'})
+    True
+    """  # noqa
 
     match = _SELECTOR_PATTERN.match(to)
 
     try:
-        selector_group = match.group(1)
+        on_selector_group = match.group(1)
+        selector_group = match.group(2)
     except AttributeError:
         raise ToStatementSyntaxError(to, message='selectors are missing')
     except IndexError:
@@ -146,4 +157,6 @@ def _extract_to_clause_selectors(to):
         raise ToStatementSyntaxError(
             to, message='spaces are not allowed in the selectors')
 
-    return {selector.strip() for selector in selector_group.split(',')}
+    return (
+        {selector.strip() for selector in on_selector_group[3:].split(',')},
+        {selector.strip() for selector in selector_group.split(',')})

snapcraft/tests/integration/general/test_build_package_grammar.py

@@ -130,6 +130,16 @@ def test_to_other_arch(self):
         self.run_snapcraft(['pull'])
         self.assertFalse(self._hello_is_installed())
 
+    def test_on_to_other_arch(self):
+        """Test that 'on to' fetches nothing when building for another arch."""
+
+        with self.modified_yaml() as yaml:
+            yaml['parts']['my-part']['build-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['hello']})
+            ]
+        self.run_snapcraft(['pull'])
+        self.assertFalse(self._hello_is_installed())
+
     def test_to_other_arch_else(self):
         """Test that 'to' moves to the 'else' branch if on other arch."""
 
@@ -141,6 +151,17 @@ def test_to_other_arch_else(self):
         self.run_snapcraft(['pull'])
         self.assertTrue(self._hello_is_installed())
 
+    def test_on_to_other_arch_else(self):
+        """Test that 'on to' moves to the 'else' branch if on other arch."""
+
+        with self.modified_yaml() as yaml:
+            yaml['parts']['my-part']['build-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['foo']}),
+                OrderedDict({'else': ['hello']})
+            ]
+        self.run_snapcraft(['pull'])
+        self.assertTrue(self._hello_is_installed())
+
     def test_to_other_arch_else_fail(self):
         """Test that 'on' fails with an error if it hits an 'else fail'."""
 
@@ -154,6 +175,19 @@ def test_to_other_arch_else_fail(self):
             ['pull']).output, Contains(
                 "Unable to satisfy 'to other-arch', failure forced"))
 
+    def test_on_to_other_arch_else_fail(self):
+        """Test that 'on to' fails with an error if it hits an 'else fail'."""
+
+        with self.modified_yaml() as yaml:
+            yaml['parts']['my-part']['build-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['foo']}),
+                'else fail'
+            ]
+        self.assertThat(self.assertRaises(
+            subprocess.CalledProcessError, self.run_snapcraft,
+            ['pull']).output, Contains(
+                "Unable to satisfy 'to other-arch', failure forced"))
+
     def test_global_build_package_to_other_arch_else(self):
         """Test that grammar works in global build packages as well."""
 
@@ -164,3 +198,14 @@ def test_global_build_package_to_other_arch_else(self):
             ]
         self.run_snapcraft(['pull'])
         self.assertTrue(self._hello_is_installed())
+
+    def test_global_build_package_on_to_other_arch_else(self):
+        """Test that grammar works in global build packages as well."""
+
+        with self.modified_yaml('build-package-grammar-global') as yaml:
+            yaml['build-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['foo']}),
+                OrderedDict({'else': ['hello']}),
+            ]
+        self.run_snapcraft(['pull'])
+        self.assertTrue(self._hello_is_installed())

snapcraft/tests/integration/general/test_stage_package_grammar.py

@@ -118,6 +118,18 @@ def test_to_other_arch(self):
             os.path.join('prime', 'usr', 'bin', 'hello'),
             Not(FileExists()))
 
+    def test_on_to_other_arch(self):
+        """Test that 'on to' for the other arch fetches nothing."""
+
+        with self.modified_yaml() as yaml:
+            yaml['parts']['simple']['stage-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['hello']}),
+            ]
+        self.run_snapcraft(['prime', 'simple'])
+        self.assertThat(
+            os.path.join('prime', 'usr', 'bin', 'hello'),
+            Not(FileExists()))
+
     def test_to_other_arch_else(self):
         """Test that 'else' for the other arch fetches hello."""
 
@@ -131,6 +143,19 @@ def test_to_other_arch_else(self):
             os.path.join('prime', 'usr', 'bin', 'hello'),
             FileExists())
 
+    def test_on_to_other_arch_else(self):
+        """Test that 'else' for the other arch fetches hello."""
+
+        with self.modified_yaml() as yaml:
+            yaml['parts']['simple']['stage-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['foo']}),
+                OrderedDict({'else': ['hello']}),
+            ]
+        self.run_snapcraft(['prime', 'simple'])
+        self.assertThat(
+            os.path.join('prime', 'usr', 'bin', 'hello'),
+            FileExists())
+
     def test_to_other_arch_else_fail(self):
         """Test that 'else' for the other arch fails."""
 
@@ -145,3 +170,18 @@ def test_to_other_arch_else_fail(self):
 
         self.assertThat(exception.output, Contains(
             "Unable to satisfy 'to other-arch', failure forced"))
+
+    def test_on_to_other_arch_else_fail(self):
+        """Test that 'else' for the other arch fails."""
+
+        with self.modified_yaml() as yaml:
+            yaml['parts']['simple']['stage-packages'] = [
+                OrderedDict({'on i386 to other-arch': ['foo']}),
+                'else fail',
+            ]
+        exception = self.assertRaises(
+            subprocess.CalledProcessError, self.run_snapcraft,
+            ['prime', 'simple'])
+
+        self.assertThat(exception.output, Contains(
+            "Unable to satisfy 'to other-arch', failure forced"))

snapcraft/tests/unit/project_loader/grammar/test_to_statement.py

@@ -173,6 +173,22 @@ class ToStatementGrammarTestCase(GrammarTestCase):
             'target_arch': 'i386',
             'expected_packages': {'baz'}
         }),
+        ('on amd64 to armhf', {
+            'to': 'on amd64 to armhf',
+            'body': ['foo'],
+            'else_bodies': [],
+            'target_arch': 'armhf',
+            'expected_packages': {'foo:armhf'}
+        }),
+        ('on i386 to armhf, used else', {
+            'to': 'on i386 to armhf',
+            'body': ['foo'],
+            'else_bodies': [
+                ['bar']
+            ],
+            'target_arch': 'armhf',
+            'expected_packages': {'bar'}
+        }),
     ]
 
     @patch('platform.architecture')