diff options
Diffstat (limited to 'scss/expression.py')
| -rw-r--r-- | scss/expression.py | 102 |
1 files changed, 97 insertions, 5 deletions
diff --git a/scss/expression.py b/scss/expression.py index 6f85087..e16d70c 100644 --- a/scss/expression.py +++ b/scss/expression.py @@ -6,9 +6,9 @@ import operator import re import scss.config as config -from scss.cssdefs import is_builtin_css_function, _undefined_re, _units, _variable_re +from scss.cssdefs import is_builtin_css_function, _expr_glob_re, _interpolate_re, _units, _variable_re from scss.types import BooleanValue, ColorValue, ListValue, NumberValue, ParserValue, QuotedStringValue, StringValue -from scss.util import normalize_var, to_str +from scss.util import dequote, normalize_var, to_str ################################################################################ # Load C acceleration modules @@ -23,6 +23,97 @@ log = logging.getLogger(__name__) ast_cache = {} +class Calculator(object): + """Expression evaluator.""" + + def __init__(self, library): + # TODO the library should really be part of the rule + self.library = library + + def _calculate_expr(self, rule, context, options): + def __calculate_expr(result): + _group0 = result.group(1) + _base_str = _group0 + better_expr_str = eval_expr(_base_str, rule, self.library) + + if better_expr_str is None: + better_expr_str = self.apply_vars(_base_str, rule, context, options) + else: + better_expr_str = dequote(str(better_expr_str)) + + return better_expr_str + return __calculate_expr + + def do_glob_math(self, cont, rule, context=None, options=None): + """Performs #{}-interpolation. The result is always treated as a fixed + syntactic unit and will not be re-evaluated. + """ + # TODO this should really accept and/or parse an *expression* and + # return a type :| + cont = str(cont) + if '#{' not in cont: + return cont + cont = _expr_glob_re.sub(self._calculate_expr(rule, context, options), cont) + return cont + + def apply_vars(self, cont, rule, context=None, options=None): + if context is not None and isinstance(cont, basestring) and '$' in cont: + if cont in context: + # Optimization: the full cont is a variable in the context, + # flatten the interpolation and use it: + while isinstance(cont, basestring) and cont in context: + _cont = context[cont] + if _cont == cont: + break + cont = _cont + else: + # Flatten the context (no variables mapping to variables) + flat_context = {} + for k, v in context.items(): + while isinstance(v, basestring) and v in context: + _v = context[v] + if _v == v: + break + v = _v + flat_context[k] = v + + # Interpolate variables: + def _av(m): + v = flat_context.get(normalize_var(m.group(2))) + if v: + v = to_str(v) + # TODO this used to test for _dequote + if m.group(1): + v = dequote(v) + elif v is not None: + v = to_str(v) + else: + v = m.group(0) + return v + + cont = _interpolate_re.sub(_av, cont) + if options is not None: + # ...apply math: + cont = self.do_glob_math(cont, rule, context, options) + return cont + + def calculate(self, _base_str, rule, context=None, options=None): + better_expr_str = _base_str + + rule = rule.copy() + rule.context = context + rule.options = options + + better_expr_str = self.do_glob_math(better_expr_str, rule, context, options) + + better_expr_str = eval_expr(better_expr_str, rule, self.library, True) + + if better_expr_str is None: + better_expr_str = self.apply_vars(_base_str, rule, context, options) + + return better_expr_str + + def interpolate(var, rule, library): value = rule.context.get(normalize_var(var), var) if var != value and isinstance(value, basestring): @@ -60,7 +151,7 @@ def eval_expr(expr, rule, library, raw=False): results = ast.evaluate(rule, library) else: try: - P = Calculator(CalculatorScanner()) + P = CalculatorParser(CalculatorScanner()) P.reset(expr) ast = P.goal() except SyntaxError: @@ -82,6 +173,7 @@ def eval_expr(expr, rule, library, raw=False): return results +# ------------------------------------------------------------------------------ # Expression classes -- the AST resulting from a parse class Expression(object): @@ -311,7 +403,7 @@ class CalculatorScanner(Scanner): super(CalculatorScanner, self).__init__(None, ['[ \r\t\n]+'], input) -class Calculator(Parser): +class CalculatorParser(Parser): def goal(self): expr_lst = self.expr_lst() v = expr_lst @@ -524,4 +616,4 @@ class Calculator(Parser): ### Grammar ends. ################################################################################ -__all__ = ('interpolate', 'call', 'eval_expr', 'Calculator') +__all__ = ('interpolate', 'eval_expr', 'Calculator') |