eric7/DebugClients/Python/coverage/templite.py

branch
eric7
changeset 8312
800c432b34c8
parent 7427
362cd1b6f81a
child 8775
0802ae193343
diff -r 4e8b98454baa -r 800c432b34c8 eric7/DebugClients/Python/coverage/templite.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/eric7/DebugClients/Python/coverage/templite.py	Sat May 15 18:45:04 2021 +0200
@@ -0,0 +1,302 @@
+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
+
+"""A simple Python template renderer, for a nano-subset of Django syntax.
+
+For a detailed discussion of this code, see this chapter from 500 Lines:
+http://aosabook.org/en/500L/a-template-engine.html
+
+"""
+
+# Coincidentally named the same as http://code.activestate.com/recipes/496702/
+
+import re
+
+from coverage import env
+
+
+class TempliteSyntaxError(ValueError):
+    """Raised when a template has a syntax error."""
+    pass
+
+
+class TempliteValueError(ValueError):
+    """Raised when an expression won't evaluate in a template."""
+    pass
+
+
+class CodeBuilder(object):
+    """Build source code conveniently."""
+
+    def __init__(self, indent=0):
+        self.code = []
+        self.indent_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.
+
+        Indentation and newline will be added for you, don't provide them.
+
+        """
+        self.code.extend([" " * self.indent_level, line, "\n"])
+
+    def add_section(self):
+        """Add a section, a sub-CodeBuilder."""
+        section = CodeBuilder(self.indent_level)
+        self.code.append(section)
+        return section
+
+    INDENT_STEP = 4      # PEP8 says so!
+
+    def indent(self):
+        """Increase the current indent for following lines."""
+        self.indent_level += self.INDENT_STEP
+
+    def dedent(self):
+        """Decrease the current indent for following lines."""
+        self.indent_level -= self.INDENT_STEP
+
+    def get_globals(self):
+        """Execute 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_level == 0
+        # Get the Python source as a single string.
+        python_source = str(self)
+        # Execute the source, defining globals, and return them.
+        global_namespace = {}
+        exec(python_source, global_namespace)
+        return global_namespace
+
+
+class Templite(object):
+    """A simple template renderer, for a nano-subset of Django syntax.
+
+    Supported constructs are extended variable access::
+
+        {{var.modifier.modifier|filter|filter}}
+
+    loops::
+
+        {% for var in list %}...{% endfor %}
+
+    and ifs::
+
+        {% if var %}...{% endif %}
+
+    Comments are within curly-hash markers::
+
+        {# This will be ignored #}
+
+    Lines between `{% joined %}` and `{% endjoined %}` will have lines stripped
+    and joined.  Be careful, this could join words together!
+
+    Any of these constructs can have a hyphen at the end (`-}}`, `-%}`, `-#}`),
+    which will collapse the whitespace following the tag.
+
+    Construct a Templite with the template text, then use `render` against a
+    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):
+        """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.context = {}
+        for context in contexts:
+            self.context.update(context)
+
+        self.all_vars = set()
+        self.loop_vars = set()
+
+        # 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_function(context, do_dots):")
+        code.indent()
+        vars_code = code.add_section()
+        code.add_line("result = []")
+        code.add_line("append_result = result.append")
+        code.add_line("extend_result = result.extend")
+        if env.PY2:
+            code.add_line("to_str = unicode")
+        else:
+            code.add_line("to_str = str")
+
+        buffered = []
+
+        def flush_output():
+            """Force `buffered` to the code builder."""
+            if len(buffered) == 1:
+                code.add_line("append_result(%s)" % buffered[0])
+            elif len(buffered) > 1:
+                code.add_line("extend_result([%s])" % ", ".join(buffered))
+            del buffered[:]
+
+        ops_stack = []
+
+        # Split the text to form a list of tokens.
+        tokens = re.split(r"(?s)({{.*?}}|{%.*?%}|{#.*?#})", text)
+
+        squash = in_joined = False
+
+        for token in tokens:
+            if token.startswith('{'):
+                start, end = 2, -2
+                squash = (token[-3] == '-')
+                if squash:
+                    end = -3
+
+                if token.startswith('{#'):
+                    # Comment: ignore it and move on.
+                    continue
+                elif token.startswith('{{'):
+                    # An expression to evaluate.
+                    expr = self._expr_code(token[start:end].strip())
+                    buffered.append("to_str(%s)" % expr)
+                else:
+                    # token.startswith('{%')
+                    # Action tag: split into words and parse further.
+                    flush_output()
+
+                    words = token[start:end].strip().split()
+                    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)
+                        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.
+                        if len(words) != 4 or words[2] != 'in':
+                            self._syntax_error("Don't understand for", token)
+                        ops_stack.append('for')
+                        self._variable(words[1], self.loop_vars)
+                        code.add_line(
+                            "for c_%s in %s:" % (
+                                words[1],
+                                self._expr_code(words[3])
+                            )
+                        )
+                        code.indent()
+                    elif words[0] == 'joined':
+                        ops_stack.append('joined')
+                        in_joined = True
+                    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 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)
+                        if end_what == 'joined':
+                            in_joined = False
+                        else:
+                            code.dedent()
+                    else:
+                        self._syntax_error("Don't understand tag", words[0])
+            else:
+                # Literal content.  If it isn't empty, output it.
+                if in_joined:
+                    token = re.sub(r"\s*\n\s*", "", token.strip())
+                elif squash:
+                    token = token.lstrip()
+                if 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 = context[%r]" % (var_name, var_name))
+
+        code.add_line('return "".join(result)')
+        code.dedent()
+        self._render_function = code.get_globals()['render_function']
+
+    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._variable(func, self.all_vars)
+                code = "c_%s(%s)" % (func, code)
+        elif "." in expr:
+            dots = expr.split(".")
+            code = self._expr_code(dots[0])
+            args = ", ".join(repr(d) for d in dots[1:])
+            code = "do_dots(%s, %s)" % (code, args)
+        else:
+            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`.
+
+        `context` is a dictionary of values to use in this rendering.
+
+        """
+        # Make the complete context we'll use.
+        render_context = dict(self.context)
+        if context:
+            render_context.update(context)
+        return self._render_function(render_context, self._do_dots)
+
+    def _do_dots(self, value, *dots):
+        """Evaluate dotted expressions at run-time."""
+        for dot in dots:
+            try:
+                value = getattr(value, dot)
+            except AttributeError:
+                try:
+                    value = value[dot]
+                except (TypeError, KeyError):
+                    raise TempliteValueError(
+                        "Couldn't evaluate %r.%s" % (value, dot)
+                    )
+            if callable(value):
+                value = value()
+        return value

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