Coverage.py to separate dir

python/helpers/coveragepy/coverage/templite.py

@@ -0,0 +1,208 @@
+"""A simple Python template renderer, for a nano-subset of Django syntax."""
+
+# Coincidentally named the same as http://code.activestate.com/recipes/496702/
+
+import re
+
+from coverage.backward import set                       # pylint: disable=W0622
+
+
+class CodeBuilder(object):
+    """Build source code conveniently."""
+
+    def __init__(self, indent=0):
+        self.code = []
+        self.indent_amount = indent
+
+    def add_line(self, line):
+        """Add a line of source to the code.
+
+        Don't include indentations or newlines.
+
+        """
+        self.code.append(" " * self.indent_amount)
+        self.code.append(line)
+        self.code.append("\n")
+
+    def add_section(self):
+        """Add a section, a sub-CodeBuilder."""
+        sect = CodeBuilder(self.indent_amount)
+        self.code.append(sect)
+        return sect
+
+    def indent(self):
+        """Increase the current indent for following lines."""
+        self.indent_amount += 4
+
+    def dedent(self):
+        """Decrease the current indent for following lines."""
+        self.indent_amount -= 4
+
+    def __str__(self):
+        return "".join([str(c) for c in self.code])
+
+    def get_function(self, fn_name):
+        """Compile the code, and return the function `fn_name`."""
+        assert self.indent_amount == 0
+        g = {}
+        code_text = str(self)
+        exec(code_text, g)
+        return g[fn_name]
+
+
+class Templite(object):
+    """A simple template renderer, for a nano-subset of Django syntax.
+
+    Supported constructs are extended variable access::
+
+        {{var.modifer.modifier|filter|filter}}
+
+    loops::
+
+        {% for var in list %}...{% endfor %}
+
+    and ifs::
+
+        {% if var %}...{% endif %}
+
+    Comments are within curly-hash markers::
+
+        {# This will be ignored #}
+
+    Construct a Templite with the template text, then use `render` against a
+    dictionary context to create a finished string.
+
+    """
+    def __init__(self, text, *contexts):
+        """Construct a Templite with the given `text`.
+
+        `contexts` are dictionaries of values to use for future renderings.
+        These are good for filters and global values.
+
+        """
+        self.text = text
+        self.context = {}
+        for context in contexts:
+            self.context.update(context)
+
+        # We construct a function in source form, then compile it and hold onto
+        # it, and execute it to render the template.
+        code = CodeBuilder()
+
+        code.add_line("def render(ctx, dot):")
+        code.indent()
+        vars_code = code.add_section()
+        self.all_vars = set()
+        self.loop_vars = set()
+        code.add_line("result = []")
+        code.add_line("a = result.append")
+        code.add_line("e = result.extend")
+        code.add_line("s = str")
+
+        buffered = []
+        def flush_output():
+            """Force `buffered` to the code builder."""
+            if len(buffered) == 1:
+                code.add_line("a(%s)" % buffered[0])
+            elif len(buffered) > 1:
+                code.add_line("e([%s])" % ",".join(buffered))
+            del buffered[:]
+
+        # Split the text to form a list of tokens.
+        toks = re.split(r"(?s)({{.*?}}|{%.*?%}|{#.*?#})", text)
+
+        ops_stack = []
+        for tok in toks:
+            if tok.startswith('{{'):
+                # An expression to evaluate.
+                buffered.append("s(%s)" % self.expr_code(tok[2:-2].strip()))
+            elif tok.startswith('{#'):
+                # Comment: ignore it and move on.
+                continue
+            elif tok.startswith('{%'):
+                # Action tag: split into words and parse further.
+                flush_output()
+                words = tok[2:-2].strip().split()
+                if words[0] == 'if':
+                    # An if statement: evaluate the expression to determine if.
+                    assert len(words) == 2
+                    ops_stack.append('if')
+                    code.add_line("if %s:" % self.expr_code(words[1]))
+                    code.indent()
+                elif words[0] == 'for':
+                    # A loop: iterate over expression result.
+                    assert len(words) == 4 and words[2] == 'in'
+                    ops_stack.append('for')
+                    self.loop_vars.add(words[1])
+                    code.add_line(
+                        "for c_%s in %s:" % (
+                            words[1],
+                            self.expr_code(words[3])
+                        )
+                    )
+                    code.indent()
+                elif words[0].startswith('end'):
+                    # Endsomething.  Pop the ops stack
+                    end_what = words[0][3:]
+                    if ops_stack[-1] != end_what:
+                        raise SyntaxError("Mismatched end tag: %r" % end_what)
+                    ops_stack.pop()
+                    code.dedent()
+                else:
+                    raise SyntaxError("Don't understand tag: %r" % words[0])
+            else:
+                # Literal content.  If it isn't empty, output it.
+                if tok:
+                    buffered.append("%r" % tok)
+        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:
+            raise SyntaxError("Unmatched action tag: %r" % ops_stack[-1])
+
+        code.add_line("return ''.join(result)")
+        code.dedent()
+        self.render_function = code.get_function('render')
+
+    def expr_code(self, expr):
+        """Generate a Python expression for `expr`."""
+        if "|" in expr:
+            pipes = expr.split("|")
+            code = self.expr_code(pipes[0])
+            for func in pipes[1:]:
+                self.all_vars.add(func)
+                code = "c_%s(%s)" % (func, code)
+        elif "." in expr:
+            dots = expr.split(".")
+            code = self.expr_code(dots[0])
+            args = [repr(d) for d in dots[1:]]
+            code = "dot(%s, %s)" % (code, ", ".join(args))
+        else:
+            self.all_vars.add(expr)
+            code = "c_%s" % expr
+        return code
+
+    def render(self, context=None):
+        """Render this template by applying it to `context`.
+
+        `context` is a dictionary of values to use in this rendering.
+
+        """
+        # Make the complete context we'll use.
+        ctx = dict(self.context)
+        if context:
+            ctx.update(context)
+        return self.render_function(ctx, self.do_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__'):
+                value = value()
+        return value