intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 178 insertions, 0 deletions

diff --git a/contrib/tools/python3/src/Lib/codeop.py b/contrib/tools/python3/src/Lib/codeop.py
new file mode 100644
index 00000000000..4c10470aee7
--- /dev/null
+++ b/contrib/tools/python3/src/Lib/codeop.py
@@ -0,0 +1,178 @@
+r"""Utilities to compile possibly incomplete Python source code.
+
+This module provides two interfaces, broadly similar to the builtin
+function compile(), which take program text, a filename and a 'mode'
+and:
+
+- Return code object if the command is complete and valid
+- Return None if the command is incomplete
+- Raise SyntaxError, ValueError or OverflowError if the command is a
+  syntax error (OverflowError and ValueError can be produced by
+  malformed literals).
+
+Approach:
+
+First, check if the source consists entirely of blank lines and
+comments; if so, replace it with 'pass', because the built-in
+parser doesn't always do the right thing for these.
+
+Compile three times: as is, with \n, and with \n\n appended.  If it
+compiles as is, it's complete.  If it compiles with one \n appended,
+we expect more.  If it doesn't compile either way, we compare the
+error we get when compiling with \n or \n\n appended.  If the errors
+are the same, the code is broken.  But if the errors are different, we
+expect more.  Not intuitive; not even guaranteed to hold in future
+releases; but this matches the compiler's behavior from Python 1.4
+through 2.2, at least.
+
+Caveat:
+
+It is possible (but not likely) that the parser stops parsing with a
+successful outcome before reaching the end of the source; in this
+case, trailing symbols may be ignored instead of causing an error.
+For example, a backslash followed by two newlines may be followed by
+arbitrary garbage.  This will be fixed once the API for the parser is
+better.
+
+The two interfaces are:
+
+compile_command(source, filename, symbol):
+
+    Compiles a single command in the manner described above.
+
+CommandCompiler():
+
+    Instances of this class have __call__ methods identical in
+    signature to compile_command; the difference is that if the
+    instance compiles program text containing a __future__ statement,
+    the instance 'remembers' and compiles all subsequent program texts
+    with the statement in force.
+
+The module also provides another class:
+
+Compile():
+
+    Instances of this class act like the built-in function compile,
+    but with 'memory' in the sense described above.
+"""
+
+import __future__
+import warnings
+
+_features = [getattr(__future__, fname)
+             for fname in __future__.all_feature_names]
+
+__all__ = ["compile_command", "Compile", "CommandCompiler"]
+
+PyCF_DONT_IMPLY_DEDENT = 0x200          # Matches pythonrun.h
+
+def _maybe_compile(compiler, source, filename, symbol):
+    # Check for source consisting of only blank lines and comments
+    for line in source.split("\n"):
+        line = line.strip()
+        if line and line[0] != '#':
+            break               # Leave it alone
+    else:
+        if symbol != "eval":
+            source = "pass"     # Replace it with a 'pass' statement
+
+    err = err1 = err2 = None
+    code = code1 = code2 = None
+
+    try:
+        code = compiler(source, filename, symbol)
+    except SyntaxError:
+        pass
+
+    # Catch syntax warnings after the first compile
+    # to emit warnings (SyntaxWarning, DeprecationWarning) at most once.
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+
+        try:
+            code1 = compiler(source + "\n", filename, symbol)
+        except SyntaxError as e:
+            err1 = e
+
+        try:
+            code2 = compiler(source + "\n\n", filename, symbol)
+        except SyntaxError as e:
+            err2 = e
+
+    try:
+        if code:
+            return code
+        if not code1 and repr(err1) == repr(err2):
+            raise err1
+    finally:
+        err1 = err2 = None
+
+def _compile(source, filename, symbol):
+    return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT)
+
+def compile_command(source, filename="<input>", symbol="single"):
+    r"""Compile a command and determine whether it is incomplete.
+
+    Arguments:
+
+    source -- the source string; may contain \n characters
+    filename -- optional filename from which source was read; default
+                "<input>"
+    symbol -- optional grammar start symbol; "single" (default), "exec"
+              or "eval"
+
+    Return value / exceptions raised:
+
+    - Return a code object if the command is complete and valid
+    - Return None if the command is incomplete
+    - Raise SyntaxError, ValueError or OverflowError if the command is a
+      syntax error (OverflowError and ValueError can be produced by
+      malformed literals).
+    """
+    return _maybe_compile(_compile, source, filename, symbol)
+
+class Compile:
+    """Instances of this class behave much like the built-in compile
+    function, but if one is used to compile text containing a future
+    statement, it "remembers" and compiles all subsequent program texts
+    with the statement in force."""
+    def __init__(self):
+        self.flags = PyCF_DONT_IMPLY_DEDENT
+
+    def __call__(self, source, filename, symbol):
+        codeob = compile(source, filename, symbol, self.flags, True)
+        for feature in _features:
+            if codeob.co_flags & feature.compiler_flag:
+                self.flags |= feature.compiler_flag
+        return codeob
+
+class CommandCompiler:
+    """Instances of this class have __call__ methods identical in
+    signature to compile_command; the difference is that if the
+    instance compiles program text containing a __future__ statement,
+    the instance 'remembers' and compiles all subsequent program texts
+    with the statement in force."""
+
+    def __init__(self,):
+        self.compiler = Compile()
+
+    def __call__(self, source, filename="<input>", symbol="single"):
+        r"""Compile a command and determine whether it is incomplete.
+
+        Arguments:
+
+        source -- the source string; may contain \n characters
+        filename -- optional filename from which source was read;
+                    default "<input>"
+        symbol -- optional grammar start symbol; "single" (default) or
+                  "eval"
+
+        Return value / exceptions raised:
+
+        - Return a code object if the command is complete and valid
+        - Return None if the command is incomplete
+        - Raise SyntaxError, ValueError or OverflowError if the command is a
+          syntax error (OverflowError and ValueError can be produced by
+          malformed literals).
+        """
+        return _maybe_compile(self.compiler, source, filename, symbol)