Refactor to reduce coupling.

* Make ParsedLine record the type of line
* Split handle_line to allow passing arguments only where needed
* Remove unneeded attributes from ParsedRequirement

src/pip/_internal/req/req_file.py

@@ -87,49 +87,46 @@ SUPPORTED_OPTIONS_REQ_DEST = [str(o().dest) for o in SUPPORTED_OPTIONS_REQ]
 class ParsedRequirement(object):
     def __init__(
         self,
+        requirement,  # type:str
         is_editable,  # type: bool
         comes_from,  # type: str
-        use_pep517,  # type: Optional[bool]
-        isolated,  # type: bool
-        wheel_cache,  # type: Optional[WheelCache]
         constraint,  # type: bool
-        args=None,  # type: Optional[str]
-        editables=None,  # type: Optional[str]
         options=None,  # type: Optional[Dict[str, Any]]
         line_source=None,  # type: Optional[str]
     ):
         # type: (...) -> None
-        self.args = args
+        self.requirement = requirement
-        self.editables = editables
         self.is_editable = is_editable
         self.comes_from = comes_from
-        self.use_pep517 = use_pep517
-        self.isolated = isolated
         self.options = options
-        self.wheel_cache = wheel_cache
         self.constraint = constraint
         self.line_source = line_source
 
-    def make_requirement(self):
+    def make_requirement(
+        self,
+        isolated=False,  # type: bool
+        wheel_cache=None,  # type: Optional[WheelCache]
+        use_pep517=None  # type: Optional[bool]
+    ):
         # type: (...) -> InstallRequirement
         if self.is_editable:
             req = install_req_from_editable(
-                self.editables,
+                self.requirement,
                 comes_from=self.comes_from,
-                use_pep517=self.use_pep517,
+                use_pep517=use_pep517,
                 constraint=self.constraint,
-                isolated=self.isolated,
+                isolated=isolated,
-                wheel_cache=self.wheel_cache
+                wheel_cache=wheel_cache
             )
 
         else:
             req = install_req_from_line(
-                self.args,
+                self.requirement,
                 comes_from=self.comes_from,
-                use_pep517=self.use_pep517,
+                use_pep517=use_pep517,
-                isolated=self.isolated,
+                isolated=isolated,
                 options=self.options,
-                wheel_cache=self.wheel_cache,
+                wheel_cache=wheel_cache,
                 constraint=self.constraint,
                 line_source=self.line_source,
             )
@@ -150,10 +147,21 @@ class ParsedLine(object):
         self.filename = filename
         self.lineno = lineno
         self.comes_from = comes_from
-        self.args = args
         self.opts = opts
         self.constraint = constraint
 
+        if args:
+            self.is_requirement = True
+            self.is_editable = False
+            self.requirement = args
+        elif opts.editables:
+            self.is_requirement = True
+            self.is_editable = True
+            # We don't support multiple -e on one line
+            self.requirement = opts.editables[0]
+        else:
+            self.is_requirement = False
+
 
 def parse_requirements(
     filename,  # type: str
@@ -188,10 +196,18 @@ def parse_requirements(
 
     for parsed_line in parser.parse(filename, constraint):
         parsed_req = handle_line(
-            parsed_line, finder, options, session, wheel_cache, use_pep517
+            parsed_line,
+            options=options,
+            finder=finder,
+            session=session
         )
         if parsed_req is not None:
-            yield parsed_req.make_requirement()
+            isolated = options.isolated_mode if options else False
+            yield parsed_req.make_requirement(
+                isolated,
+                wheel_cache,
+                use_pep517
+            )
 
 
 def preprocess(content, skip_requirements_regex):
@@ -210,18 +226,118 @@ def preprocess(content, skip_requirements_regex):
     return lines_enum
 
 
-def handle_line(
+def handle_requirement_line(
     line,  # type: ParsedLine
+    options=None,  # type: Optional[optparse.Values]
+):
+    # type: (...) -> ParsedRequirement
+
+    # preserve for the nested code path
+    line_comes_from = '{} {} (line {})'.format(
+        '-c' if line.constraint else '-r', line.filename, line.lineno,
+    )
+
+    assert line.is_requirement
+
+    if line.is_editable:
+        # For editable requirements, we don't support per-requirement
+        # options, so just return the parsed requirement.
+        return ParsedRequirement(
+            requirement=line.requirement,
+            is_editable=line.is_editable,
+            comes_from=line_comes_from,
+            constraint=line.constraint,
+        )
+    else:
+        if options:
+            # Disable wheels if the user has specified build options
+            cmdoptions.check_install_build_global(options, line.opts)
+
+        # get the options that apply to requirements
+        req_options = {}
+        for dest in SUPPORTED_OPTIONS_REQ_DEST:
+            if dest in line.opts.__dict__ and line.opts.__dict__[dest]:
+                req_options[dest] = line.opts.__dict__[dest]
+
+        line_source = 'line {} of {}'.format(line.lineno, line.filename)
+        return ParsedRequirement(
+            requirement=line.requirement,
+            is_editable=line.is_editable,
+            comes_from=line_comes_from,
+            constraint=line.constraint,
+            options=req_options,
+            line_source=line_source,
+        )
+
+
+def handle_option_line(
+    opts,  # type: Values
+    filename,  # type: str
+    lineno,  # type: int
     finder=None,  # type: Optional[PackageFinder]
     options=None,  # type: Optional[optparse.Values]
     session=None,  # type: Optional[PipSession]
-    wheel_cache=None,  # type: Optional[WheelCache]
+):
-    use_pep517=None,  # type: Optional[bool]
+    # type:  (...) -> None
+
+    # percolate hash-checking option upward
+    if opts.require_hashes:
+        options.require_hashes = opts.require_hashes
+
+    # set finder options
+    elif finder:
+        find_links = finder.find_links
+        index_urls = finder.index_urls
+        if opts.index_url:
+            index_urls = [opts.index_url]
+        if opts.no_index is True:
+            index_urls = []
+        if opts.extra_index_urls:
+            index_urls.extend(opts.extra_index_urls)
+        if opts.find_links:
+            # FIXME: it would be nice to keep track of the source
+            # of the find_links: support a find-links local path
+            # relative to a requirements file.
+            value = opts.find_links[0]
+            req_dir = os.path.dirname(os.path.abspath(filename))
+            relative_to_reqs_file = os.path.join(req_dir, value)
+            if os.path.exists(relative_to_reqs_file):
+                value = relative_to_reqs_file
+            find_links.append(value)
+
+        search_scope = SearchScope(
+            find_links=find_links,
+            index_urls=index_urls,
+        )
+        finder.search_scope = search_scope
+
+        if opts.pre:
+            finder.set_allow_all_prereleases()
+
+        if session:
+            for host in opts.trusted_hosts or []:
+                source = 'line {} of {}'.format(lineno, filename)
+                session.add_trusted_host(host, source=source)
+
+
+def handle_line(
+    line,  # type: ParsedLine
+    options=None,  # type: Optional[optparse.Values]
+    finder=None,  # type: Optional[PackageFinder]
+    session=None,  # type: Optional[PipSession]
 ):
     # type: (...) -> Optional[ParsedRequirement]
     """Handle a single parsed requirements line; This can result in
     creating/yielding requirements, or updating the finder.
 
+    :param line:        The parsed line to be processed.
+    :param options:     CLI options.
+    :param finder:      The finder - updated by non-requirement lines.
+    :param session:     The session - updated by non-requirement lines.
+
+    Returns a ParsedRequirement object if the line is a requirement line,
+    otherwise returns None.
+
     For lines that contain requirements, the only options that have an effect
     are from SUPPORTED_OPTIONS_REQ, and they are scoped to the
     requirement. Other options from SUPPORTED_OPTIONS may be present, but are
@@ -234,87 +350,19 @@ def handle_line(
     affect the finder.
     """
 
-    # preserve for the nested code path
+    if parsed_line.is_requirement:
-    line_comes_from = '{} {} (line {})'.format(
+        parsed_req = handle_requirement_line(parsed_line, options)
-        '-c' if line.constraint else '-r', line.filename, line.lineno,
+        return parsed_req
-    )
+    else:
-
+        handle_option_line(
-    # return a line requirement
+            parsed_line.opts,
-    if line.args:
+            parsed_line.filename,
-        isolated = options.isolated_mode if options else False
+            parsed_line.lineno,
-        if options:
+            finder,
-            cmdoptions.check_install_build_global(options, line.opts)
+            options,
-        # get the options that apply to requirements
+            session,
-        req_options = {}
-        for dest in SUPPORTED_OPTIONS_REQ_DEST:
-            if dest in line.opts.__dict__ and line.opts.__dict__[dest]:
-                req_options[dest] = line.opts.__dict__[dest]
-        line_source = 'line {} of {}'.format(line.lineno, line.filename)
-        return ParsedRequirement(
-            args=line.args,
-            is_editable=False,
-            comes_from=line_comes_from,
-            use_pep517=use_pep517,
-            isolated=isolated,
-            options=req_options,
-            wheel_cache=wheel_cache,
-            constraint=line.constraint,
-            line_source=line_source,
         )
-
+        return None
-    # return an editable requirement
-    elif line.opts.editables:
-        isolated = options.isolated_mode if options else False
-        return ParsedRequirement(
-            editables=line.opts.editables[0],
-            is_editable=True,
-            comes_from=line_comes_from,
-            use_pep517=use_pep517,
-            constraint=line.constraint,
-            isolated=isolated,
-            wheel_cache=wheel_cache
-        )
-
-    # percolate hash-checking option upward
-    elif line.opts.require_hashes:
-        options.require_hashes = line.opts.require_hashes
-
-    # set finder options
-    elif finder:
-        find_links = finder.find_links
-        index_urls = finder.index_urls
-        if line.opts.index_url:
-            index_urls = [line.opts.index_url]
-        if line.opts.no_index is True:
-            index_urls = []
-        if line.opts.extra_index_urls:
-            index_urls.extend(line.opts.extra_index_urls)
-        if line.opts.find_links:
-            # FIXME: it would be nice to keep track of the source
-            # of the find_links: support a find-links local path
-            # relative to a requirements file.
-            value = line.opts.find_links[0]
-            req_dir = os.path.dirname(os.path.abspath(line.filename))
-            relative_to_reqs_file = os.path.join(req_dir, value)
-            if os.path.exists(relative_to_reqs_file):
-                value = relative_to_reqs_file
-            find_links.append(value)
-
-        search_scope = SearchScope(
-            find_links=find_links,
-            index_urls=index_urls,
-        )
-        finder.search_scope = search_scope
-
-        if line.opts.pre:
-            finder.set_allow_all_prereleases()
-
-        if session:
-            for host in line.opts.trusted_hosts or []:
-                source = 'line {} of {}'.format(line.lineno, line.filename)
-                session.add_trusted_host(host, source=source)
-
-    return None
 
 
 class RequirementsFileParser(object):
@@ -342,8 +390,7 @@ class RequirementsFileParser(object):
         # type: (str, bool) -> Iterator[ParsedLine]
         for line in self._parse_file(filename, constraint):
             if (
-                not line.args and
+                not line.is_requirement and
-                not line.opts.editables and
                 (line.opts.requirements or line.opts.constraints)
             ):
                 # parse a nested requirements file

tests/unit/test_req.py

@@ -31,7 +31,11 @@ from pip._internal.req.constructors import (
     install_req_from_req_string,
     parse_editable,
 )
-from pip._internal.req.req_file import ParsedLine, get_line_parser, handle_line
+from pip._internal.req.req_file import (
+    ParsedLine,
+    get_line_parser,
+    handle_requirement_line,
+)
 from pip._internal.req.req_tracker import get_requirement_tracker
 from pip._internal.utils.urls import path_to_url
 from tests.lib import assert_raises_regexp, make_test_finder, requirements_file
@@ -48,7 +52,7 @@ def get_processed_req_from_line(line, fname='file', lineno=1):
         opts,
         False,
     )
-    parsed_req = handle_line(parsed_line)
+    parsed_req = handle_requirement_line(parsed_line)
     assert parsed_req is not None
     req = parsed_req.make_requirement()
     req.is_direct = True