Fix a problem with syntax coloring continued lines, and refactor for testability, and add tests. Fixes issue #30.

1 files changed, 101 insertions, 0 deletions

diff --git a/coverage/phystokens.py b/coverage/phystokens.py
new file mode 100644
index 0000000..7eebb8a
--- /dev/null
+++ b/coverage/phystokens.py
@@ -0,0 +1,101 @@
+"""Better tokenizing for coverage.py."""
+
+import keyword, re, token, tokenize
+from coverage.backward import StringIO              # pylint: disable-msg=W0622
+
+def phys_tokens(toks):
+    """Return all physical tokens, even line continuations.
+    
+    tokenize.generate_tokens() doesn't return a token for the backslash that
+    continues lines.  This wrapper provides those tokens so that we can
+    re-create a faithful representation of the original source.
+    
+    Returns the same values as generate_tokens()
+    
+    """
+    last_line = None
+    last_lineno = -1
+    for ttype, ttext, (slineno, scol), (elineno, ecol), ltext in toks:
+        if last_lineno != elineno:
+            if last_line and last_line[-2:] == "\\\n":
+                # We are at the beginning of a new line, and the last line
+                # ended with a backslash.  We probably have to inject a
+                # backslash token into the stream. Unfortunately, there's more
+                # to figure out.  This code::
+                #
+                #   usage = """\
+                #   HEY THERE
+                #   """
+                #
+                # triggers this condition, but the token text is::
+                #
+                #   '"""\\\nHEY THERE\n"""'
+                #
+                # so we need to figure out if the backslash is already in the
+                # string token or not.
+                inject_backslash = True
+                if ttype == token.STRING:
+                    if "\n" in ttext and ttext.split('\n', 1)[0][-1] == '\\':
+                        # It's a multiline string and the first line ends with
+                        # a backslash, so we don't need to inject another.
+                        inject_backslash = False
+                if inject_backslash:
+                    # Figure out what column the backslash is in.
+                    ccol = len(last_line.split("\n")[-2]) - 1
+                    # Yield the token, with a fake token type.
+                    yield (
+                        99999, "\\\n",
+                        (slineno, ccol), (slineno, ccol+2),
+                        last_line
+                        )
+            last_line = ltext
+        yield ttype, ttext, (slineno, scol), (elineno, ecol), ltext
+        last_lineno = elineno
+
+
+def source_token_lines(source):
+    """Generate a series of lines, one for each line in `source`.
+    
+    Each line is a list of pairs, each pair is a token::
+    
+        [('key', 'def'), ('ws', ' '), ('nam', 'hello'), ('op', '('), ... ]
+
+    Each pair has a token class, and the token text.
+    
+    If you concatenate all the token texts, and then join them with newlines,
+    you should have your original `source` back, with two differences:
+    trailing whitespace is not preserved, and a final line with no newline
+    is indistinguishable from a final line with a newline.
+
+    """
+    ws_tokens = [token.INDENT, token.DEDENT, token.NEWLINE, tokenize.NL]
+    line = []
+    col = 0
+    tokgen = tokenize.generate_tokens(StringIO(source).readline)
+    for ttype, ttext, (_, scol), (_, ecol), _ in phys_tokens(tokgen):
+        mark_start = True
+        for part in re.split('(\n)', ttext):
+            if part == '\n':
+                yield line
+                line = []
+                col = 0
+                mark_end = False
+            elif part == '':
+                mark_end = False
+            elif ttype in ws_tokens:
+                mark_end = False
+            else:
+                if mark_start and scol > col:
+                    line.append(("ws", " " * (scol - col)))
+                    mark_start = False
+                tok_class = tokenize.tok_name.get(ttype, 'xx').lower()[:3]
+                if ttype == token.NAME and keyword.iskeyword(ttext):
+                    tok_class = "key"
+                line.append((tok_class, part))
+                mark_end = True
+            scol = 0
+        if mark_end:
+            col = ecol
+
+    if line:
+        yield line