Refactor poetry export

Introduce a new root_package section in poetry.lock, and miscellaneous
fixes

src/poetry/repositories/base_repository.py

@@ -11,6 +11,7 @@
 class BaseRepository:
     def __init__(self) -> None:
         self._packages: List["Package"] = []
+        self.root_package: Optional["Package"] = None
 
     @property
     def packages(self) -> List["Package"]:

src/poetry/utils/exporter.py

@@ -1,6 +1,6 @@
-import itertools
 import urllib.parse
 
+from copy import deepcopy
 from typing import TYPE_CHECKING
 from typing import Optional
 from typing import Sequence
@@ -70,21 +70,37 @@ def _export_requirements_txt(
         content = ""
         dependency_lines = set()
 
-        for package, groups in itertools.groupby(
-            self._poetry.locker.get_project_dependency_packages(
-                project_requires=self._poetry.package.all_requires,
-                dev=dev,
-                extras=extras,
-            ),
-            lambda dependency_package: dependency_package.package,
+        # If we have a root package then use that to tell us what the top-level
+        # dependencies are.  If we don't (older version of poetry.lock) then try to
+        # cover all dependencies.
+        repository = self._poetry.locker.locked_repository(with_dev_reqs=dev)
+        root_package = repository.root_package
+        project_requires = (
+            self._poetry.package.all_requires
+            if root_package is None
+            else root_package.requires
+        )
+
+        # If we have a root package then we can also update the marker on each
+        # dependency to take account of the project-level python version.
+        if root_package is not None:
+            restricted_project_requires = []
+            for project_require in project_requires:
+                project_require = deepcopy(project_require)
+                project_require.marker = project_require.marker.intersect(
+                    root_package.python_marker
+                )
+                restricted_project_requires.append(project_require)
+            project_requires = restricted_project_requires
+
+        for dependency_package in self._poetry.locker.get_project_dependency_packages(
+            project_requires=project_requires,
+            dev=dev,
+            extras=extras,
         ):
             line = ""
-            dependency_packages = list(groups)
-            dependency = dependency_packages[0].dependency
-            marker = dependency.marker
-            for dep_package in dependency_packages[1:]:
-                marker = marker.union(dep_package.dependency.marker)
-            dependency.marker = marker
+            dependency = dependency_package.dependency
+            package = dependency_package.package
 
             if package.develop:
                 line += "-e "

tests/console/commands/test_export.py

@@ -81,9 +81,7 @@ def _export_requirements(tester: "CommandTester", poetry: "Poetry") -> None:
 
     assert poetry.locker.lock.exists()
 
-    expected = """\
-foo==1.0.0
-"""
+    expected = 'foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.4" and python_version < "4.0"\n'  # noqa: E501
 
     assert content == expected
 
@@ -110,28 +108,24 @@ def test_export_fails_on_invalid_format(tester: "CommandTester", do_lock: None):
 
 def test_export_prints_to_stdout_by_default(tester: "CommandTester", do_lock: None):
     tester.execute("--format requirements.txt")
-    expected = """\
-foo==1.0.0
-"""
+    expected = 'foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.4" and python_version < "4.0"\n'  # noqa: E501
     assert tester.io.fetch_output() == expected
 
 
 def test_export_uses_requirements_txt_format_by_default(
     tester: "CommandTester", do_lock: None
 ):
     tester.execute()
-    expected = """\
-foo==1.0.0
-"""
+    expected = 'foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.4" and python_version < "4.0"\n'  # noqa: E501
     assert tester.io.fetch_output() == expected
 
 
 def test_export_includes_extras_by_flag(tester: "CommandTester", do_lock: None):
     tester.execute("--format requirements.txt --extras feature_bar")
-    expected = """\
-bar==1.1.0
-foo==1.0.0
-"""
+    expected = (
+        'bar==1.1.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.4" and python_version < "4.0"\n'  # noqa: E501
+        'foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.4" and python_version < "4.0"\n'  # noqa: E501
+    )
     assert tester.io.fetch_output() == expected
 
 

tests/installation/fixtures/extras-with-dependencies.test

@@ -1,3 +1,18 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+extras = { foo = ['c'] }
+
+[root_package.dependencies]
+A = "^1.0"
+B = "^1.0"
+C = { optional = true, version = "^1.0" }
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/extras.test

@@ -1,3 +1,19 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+extras = { foo = ['d'] }
+files = []
+
+[root_package.dependencies]
+A = "^1.0"
+B = "^1.0"
+C = "^1.0"
+D = { version = "^1.0", optional = true }
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/install-no-dev.test

@@ -1,3 +1,12 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/no-dependencies.test

@@ -1,5 +1,14 @@
 package = []
 
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
 [metadata]
 python-versions = "*"
 lock-version = "1.1"

tests/installation/fixtures/old-lock.test

@@ -1,3 +1,12 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
 [[package]]
 name = "attrs"
 version = "17.4.0"

tests/installation/fixtures/remove.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = "~1.0"
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/update-with-lock.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = "*"
+
 [[package]]
 name = "A"
 version = "1.1"

tests/installation/fixtures/update-with-locked-extras.test

@@ -1,3 +1,16 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = { version = "^1.0", extras = ['foo'] }
+D = "^1.0"
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/with-category-change.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+B = "^1.1"
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/with-conditional-dependency.test

@@ -1,3 +1,12 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
 [[package]]
 name = "A"
 version = "1.0.0"

tests/installation/fixtures/with-dependencies-extras.test

@@ -1,3 +1,16 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = "^1.0"
+B = { version = "^1.0", extras = ['foo'] }
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/with-dependencies-nested-extras.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = { version = "^1.0", extras = ['B'] }
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/with-dependencies.test

@@ -1,3 +1,16 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = "~1.0"
+B = "^1.0"
+
 [[package]]
 name = "A"
 version = "1.0"

tests/installation/fixtures/with-directory-dependency-poetry-transitive.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+project-with-transitive-directory-dependencies = { path = "project_with_transitive_directory_dependencies" }
+
 [[package]]
 category = "main"
 description = ""

tests/installation/fixtures/with-directory-dependency-poetry.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+project-with-extras = { extras = ['extras_a'], path = "tests/fixtures/project_with_extras" }
+
 [[package]]
 description = ""
 category = "main"

tests/installation/fixtures/with-directory-dependency-setuptools.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+project-with-setup = { path = "tests/fixtures/project_with_setup" }
+
 [[package]]
 name = "cachy"
 version = "0.2.0"

tests/installation/fixtures/with-duplicate-dependencies-update.test

@@ -1,3 +1,15 @@
+[root_package]
+name = "root"
+version = "1.0"
+description = ""
+category = "dev"
+optional = true
+python-versions = "*"
+files = []
+
+[root_package.dependencies]
+A = "*"
+
 [[package]]
 name = "A"
 version = "1.1"