Latest code form 500lines

2 files changed, 116 insertions, 68 deletions

diff --git a/coverage/templite.py b/coverage/templite.py
index 3f6ef0b3..a71caf63 100644
--- a/coverage/templite.py
+++ b/coverage/templite.py
@@ -5,44 +5,49 @@
 import re
 
 
+class TempliteSyntaxError(ValueError):
+    """Raised when a template has a syntax error."""
+    pass
+
+
 class CodeBuilder(object):
     """Build source code conveniently."""
 
-    INDENT_STEP = 4      # PEP8 says so!
-
     def __init__(self, indent=0):
         self.code = []
-        self.indent_amount = indent
+        self.ident_level = indent
+
+    def __str__(self):
+        return "".join(str(c) for c in self.code)
 
     def add_line(self, line):
         """Add a line of source to the code.
 
-        Don't include indentations or newlines.
+        Indentation and newline will be added for you, don't provide them.
 
         """
-        self.code.extend([" " * self.indent_amount, line, "\n"])
+        self.code.extend([" " * self.ident_level, line, "\n"])
 
-    def add_section(self):
+    def add_subbuilder(self):
         """Add a section, a sub-CodeBuilder."""
-        sect = CodeBuilder(self.indent_amount)
+        sect = CodeBuilder(self.ident_level)
         self.code.append(sect)
         return sect
 
+    INDENT_STEP = 4      # PEP8 says so!
+
     def indent(self):
         """Increase the current indent for following lines."""
-        self.indent_amount += self.INDENT_STEP
+        self.ident_level += self.INDENT_STEP
 
     def dedent(self):
         """Decrease the current indent for following lines."""
-        self.indent_amount -= self.INDENT_STEP
-
-    def __str__(self):
-        return "".join(str(c) for c in self.code)
+        self.ident_level -= self.INDENT_STEP
 
     def get_globals(self):
         """Compile the code, and return a dict of globals it defines."""
         # A check that the caller really finished all the blocks they started.
-        assert self.indent_amount == 0
+        assert self.ident_level == 0
         # Get the Python source as a single string.
         python_source = str(self)
         # Execute the source, defining globals, and return them.
@@ -71,7 +76,20 @@ class Templite(object):
         {# This will be ignored #}
 
     Construct a Templite with the template text, then use `render` against a
-    dictionary context to create a finished string.
+    dictionary context to create a finished string::
+
+        templite = Templite('''
+            <h1>Hello {{name|upper}}!</h1>
+            {% for topic in topics %}
+                <p>You are interested in {{topic}}.</p>
+            {% endif %}
+            ''',
+            {'upper': str.upper},
+        )
+        text = templite.render({
+            'name': "Ned",
+            'topics': ['Python', 'Geometry', 'Juggling'],
+        })
 
     """
     def __init__(self, text, *contexts):
@@ -81,7 +99,6 @@ class Templite(object):
         These are good for filters and global values.
 
         """
-        self.text = text
         self.context = {}
         for context in contexts:
             self.context.update(context)
@@ -93,9 +110,9 @@ class Templite(object):
         # it, and execute it to render the template.
         code = CodeBuilder()
 
-        code.add_line("def render(ctx, dot):")
+        code.add_line("def render_function(ctx, do_dots):")
         code.indent()
-        vars_code = code.add_section()
+        vars_code = code.add_subbuilder()
         code.add_line("result = []")
         code.add_line("a = result.append")
         code.add_line("e = result.extend")
@@ -107,20 +124,21 @@ class Templite(object):
             if len(buffered) == 1:
                 code.add_line("a(%s)" % buffered[0])
             elif len(buffered) > 1:
-                code.add_line("e([%s])" % ",".join(buffered))
+                code.add_line("e([%s])" % ", ".join(buffered))
             del buffered[:]
 
+        ops_stack = []
+
         # Split the text to form a list of tokens.
         tokens = re.split(r"(?s)({{.*?}}|{%.*?%}|{#.*?#})", text)
 
-        ops_stack = []
         for token in tokens:
-            if token.startswith('{{'):
-                # An expression to evaluate.
-                buffered.append("s(%s)" % self.expr_code(token[2:-2].strip()))
-            elif token.startswith('{#'):
+            if token.startswith('{#'):
                 # Comment: ignore it and move on.
                 continue
+            elif token.startswith('{{'):
+                # An expression to evaluate.
+                buffered.append("s(%s)" % self._expr_code(token[2:-2].strip()))
             elif token.startswith('{%'):
                 # Action tag: split into words and parse further.
                 flush_output()
@@ -128,70 +146,87 @@ class Templite(object):
                 if words[0] == 'if':
                     # An if statement: evaluate the expression to determine if.
                     if len(words) != 2:
-                        self.syntax_error("Don't understand if", token)
+                        self._syntax_error("Don't understand if", token)
                     ops_stack.append('if')
-                    code.add_line("if %s:" % self.expr_code(words[1]))
+                    code.add_line("if %s:" % self._expr_code(words[1]))
                     code.indent()
                 elif words[0] == 'for':
                     # A loop: iterate over expression result.
                     if len(words) != 4 or words[2] != 'in':
-                        self.syntax_error("Don't understand for", token)
+                        self._syntax_error("Don't understand for", token)
                     ops_stack.append('for')
-                    self.loop_vars.add(words[1])
+                    self._variable(words[1], self.loop_vars)
                     code.add_line(
                         "for c_%s in %s:" % (
                             words[1],
-                            self.expr_code(words[3])
+                            self._expr_code(words[3])
                         )
                     )
                     code.indent()
                 elif words[0].startswith('end'):
                     # Endsomething.  Pop the ops stack.
+                    if len(words) != 1:
+                        self._syntax_error("Don't understand end", token)
                     end_what = words[0][3:]
-                    if ops_stack[-1] != end_what:
-                        self.syntax_error("Mismatched end tag", end_what)
-                    ops_stack.pop()
+                    if not ops_stack:
+                        self._syntax_error("Too many ends", token)
+                    start_what = ops_stack.pop()
+                    if start_what != end_what:
+                        self._syntax_error("Mismatched end tag", end_what)
                     code.dedent()
                 else:
-                    self.syntax_error("Don't understand tag", words[0])
+                    self._syntax_error("Don't understand tag", words[0])
             else:
                 # Literal content.  If it isn't empty, output it.
                 if token:
-                    buffered.append("%r" % token)
+                    buffered.append(repr(token))
+
+        if ops_stack:
+            self._syntax_error("Unmatched action tag", ops_stack[-1])
+
         flush_output()
 
         for var_name in self.all_vars - self.loop_vars:
             vars_code.add_line("c_%s = ctx[%r]" % (var_name, var_name))
 
-        if ops_stack:
-            self.syntax_error("Unmatched action tag", ops_stack[-1])
-
         code.add_line("return ''.join(result)")
         code.dedent()
-        self.render_function = code.get_globals()['render']
-
-    def syntax_error(self, msg, thing):
-        """Raise a syntax error using `msg`, and showing `thing`."""
-        raise SyntaxError("%s: %r" % (msg, thing))
+        self._render_function = code.get_globals()['render_function']
 
-    def expr_code(self, expr):
+    def _expr_code(self, expr):
         """Generate a Python expression for `expr`."""
         if "|" in expr:
             pipes = expr.split("|")
-            code = self.expr_code(pipes[0])
+            code = self._expr_code(pipes[0])
             for func in pipes[1:]:
-                self.all_vars.add(func)
+                self._variable(func, self.all_vars)
                 code = "c_%s(%s)" % (func, code)
         elif "." in expr:
             dots = expr.split(".")
-            code = self.expr_code(dots[0])
+            code = self._expr_code(dots[0])
             args = ", ".join(repr(d) for d in dots[1:])
-            code = "dot(%s, %s)" % (code, args)
+            code = "do_dots(%s, %s)" % (code, args)
         else:
-            self.all_vars.add(expr)
+            self._variable(expr, self.all_vars)
             code = "c_%s" % expr
         return code
 
+    def _syntax_error(self, msg, thing):
+        """Raise a syntax error using `msg`, and showing `thing`."""
+        raise TempliteSyntaxError("%s: %r" % (msg, thing))
+
+    def _variable(self, name, vars_set):
+        """Track that `name` is used as a variable.
+
+        Adds the name to `vars_set`, a set of variable names.
+
+        Raises an syntax error if `name` is not a valid name.
+
+        """
+        if not re.match(r"[_a-zA-Z][_a-zA-Z0-9]*$", name):
+            self._syntax_error("Not a valid name", name)
+        vars_set.add(name)
+
     def render(self, context=None):
         """Render this template by applying it to `context`.
 
@@ -202,15 +237,15 @@ class Templite(object):
         ctx = dict(self.context)
         if context:
             ctx.update(context)
-        return self.render_function(ctx, self.do_dots)
+        return self._render_function(ctx, self._do_dots)
 
-    def do_dots(self, value, *dots):
+    def _do_dots(self, value, *dots):
         """Evaluate dotted expressions at runtime."""
         for dot in dots:
             try:
                 value = getattr(value, dot)
             except AttributeError:
                 value = value[dot]
-            if hasattr(value, '__call__'):
+            if callable(value):
                 value = value()
         return value
diff --git a/tests/test_templite.py b/tests/test_templite.py
index c861c2ff..4b1f6e45 100644
--- a/tests/test_templite.py
+++ b/tests/test_templite.py
@@ -1,6 +1,7 @@
 """Tests for coverage.templite."""
 
-from coverage.templite import Templite
+import re
+from coverage.templite import Templite, TempliteSyntaxError
 from tests.coveragetest import CoverageTest
 
 # pylint: disable=W0612,E1101
@@ -33,6 +34,10 @@ class TempliteTest(CoverageTest):
         if result:
             self.assertEqual(actual, result)
 
+    def assertSynErr(self, msg):
+        pat = "^" + re.escape(msg) + "$"
+        return self.assertRaisesRegexp(TempliteSyntaxError, pat)
+
     def test_passthrough(self):
         # Strings without variables are passed through unchanged.
         self.assertEqual(Templite("Hello").render(), "Hello")
@@ -231,34 +236,42 @@ class TempliteTest(CoverageTest):
                 "Hey {{foo.bar.baz}} there", {'foo': None}, "Hey ??? there"
             )
 
+    def test_bad_names(self):
+        with self.assertSynErr("Not a valid name: 'var%&!@'"):
+            self.try_render("Wat: {{ var%&!@ }}")
+        with self.assertSynErr("Not a valid name: 'filter%&!@'"):
+            self.try_render("Wat: {{ foo|filter%&!@ }}")
+        with self.assertSynErr("Not a valid name: '@'"):
+            self.try_render("Wat: {% for @ in x %}{% endfor %}")
+
     def test_bogus_tag_syntax(self):
-        msg = "Don't understand tag: 'bogus'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Don't understand tag: 'bogus'"):
             self.try_render("Huh: {% bogus %}!!{% endbogus %}??")
 
     def test_malformed_if(self):
-        msg = "Don't understand if: '{% if %}'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Don't understand if: '{% if %}'"):
             self.try_render("Buh? {% if %}hi!{% endif %}")
-        msg = "Don't understand if: '{% if this or that %}'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Don't understand if: '{% if this or that %}'"):
             self.try_render("Buh? {% if this or that %}hi!{% endif %}")
 
-    def test_malformed_for_(self):
-        msg = "Don't understand for: '{% for %}'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+    def test_malformed_for(self):
+        with self.assertSynErr("Don't understand for: '{% for %}'"):
             self.try_render("Weird: {% for %}loop{% endfor %}")
-        msg = "Don't understand for: '{% for x from y %}'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Don't understand for: '{% for x from y %}'"):
             self.try_render("Weird: {% for x from y %}loop{% endfor %}")
-        msg = "Don't understand for: '{% for x, y in z %}'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Don't understand for: '{% for x, y in z %}'"):
             self.try_render("Weird: {% for x, y in z %}loop{% endfor %}")
 
     def test_bad_nesting(self):
-        msg = "Unmatched action tag: 'if'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Unmatched action tag: 'if'"):
             self.try_render("{% if x %}X")
-        msg = "Mismatched end tag: 'for'"
-        with self.assertRaisesRegexp(SyntaxError, msg):
+        with self.assertSynErr("Mismatched end tag: 'for'"):
             self.try_render("{% if x %}X{% endfor %}")
+        with self.assertSynErr("Too many ends: '{% endif %}'"):
+            self.try_render("{% if x %}{% endif %}{% endif %}")
+
+    def test_malformed_end(self):
+        with self.assertSynErr("Don't understand end: '{% end if %}'"):
+            self.try_render("{% if x %}X{% end if %}")
+        with self.assertSynErr("Don't understand end: '{% endif now %}'"):
+            self.try_render("{% if x %}X{% endif now %}")