361 lines
11 KiB
C++
361 lines
11 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef CSSCalc_h_
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#define CSSCalc_h_
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#include "nsCSSValue.h"
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#include "nsStyleCoord.h"
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#include <math.h>
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namespace mozilla {
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namespace css {
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/**
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* ComputeCalc computes the result of a calc() expression tree.
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*
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* It is templatized over a CalcOps class that is expected to provide:
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*
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* // input_type and input_array_type have a bunch of very specific
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* // expectations (which happen to be met by two classes (nsCSSValue
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* // and nsStyleCoord). There must be methods (roughly):
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* // input_array_type* input_type::GetArrayValue();
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* // uint32_t input_array_type::Count() const;
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* // input_type& input_array_type::Item(uint32_t);
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* typedef ... input_type;
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* typedef ... input_array_type;
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*
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* typedef ... result_type;
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*
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* // GetUnit(avalue) must return the correct nsCSSUnit for any
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* // value that represents a calc tree node (eCSSUnit_Calc*). For
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* // other nodes, it may return any non eCSSUnit_Calc* unit.
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* static nsCSSUnit GetUnit(const input_type& aValue);
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*
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* result_type
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* MergeAdditive(nsCSSUnit aCalcFunction,
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* result_type aValue1, result_type aValue2);
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*
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* result_type
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* MergeMultiplicativeL(nsCSSUnit aCalcFunction,
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* float aValue1, result_type aValue2);
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*
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* result_type
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* MergeMultiplicativeR(nsCSSUnit aCalcFunction,
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* result_type aValue1, float aValue2);
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*
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* result_type
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* ComputeLeafValue(const input_type& aValue);
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*
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* float
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* ComputeNumber(const input_type& aValue);
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*
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* The CalcOps methods might compute the calc() expression down to a
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* number, reduce some parts of it to a number but replicate other
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* parts, or produce a tree with a different data structure (for
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* example, nsCSS* for specified values vs nsStyle* for computed
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* values).
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*
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* For each leaf in the calc() expression, ComputeCalc will call either
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* ComputeNumber (when the leaf is the left side of a Times_L or the
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* right side of a Times_R or Divided) or ComputeLeafValue (otherwise).
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* (The CalcOps in the CSS parser that reduces purely numeric
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* expressions in turn calls ComputeCalc on numbers; other ops can
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* presume that expressions in the number positions have already been
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* normalized to a single numeric value and derive from
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* NumbersAlreadyNormalizedCalcOps.)
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*
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* For non-leaves, one of the Merge functions will be called:
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* MergeAdditive for Plus and Minus
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* MergeMultiplicativeL for Times_L (number * value)
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* MergeMultiplicativeR for Times_R (value * number) and Divided
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*/
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template <class CalcOps>
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static typename CalcOps::result_type
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ComputeCalc(const typename CalcOps::input_type& aValue, CalcOps &aOps)
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{
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switch (CalcOps::GetUnit(aValue)) {
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case eCSSUnit_Calc: {
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typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
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MOZ_ASSERT(arr->Count() == 1, "unexpected length");
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return ComputeCalc(arr->Item(0), aOps);
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}
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case eCSSUnit_Calc_Plus:
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case eCSSUnit_Calc_Minus: {
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typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
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MOZ_ASSERT(arr->Count() == 2, "unexpected length");
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typename CalcOps::result_type lhs = ComputeCalc(arr->Item(0), aOps),
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rhs = ComputeCalc(arr->Item(1), aOps);
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return aOps.MergeAdditive(CalcOps::GetUnit(aValue), lhs, rhs);
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}
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case eCSSUnit_Calc_Times_L: {
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typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
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MOZ_ASSERT(arr->Count() == 2, "unexpected length");
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float lhs = aOps.ComputeNumber(arr->Item(0));
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typename CalcOps::result_type rhs = ComputeCalc(arr->Item(1), aOps);
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return aOps.MergeMultiplicativeL(CalcOps::GetUnit(aValue), lhs, rhs);
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}
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case eCSSUnit_Calc_Times_R:
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case eCSSUnit_Calc_Divided: {
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typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
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MOZ_ASSERT(arr->Count() == 2, "unexpected length");
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typename CalcOps::result_type lhs = ComputeCalc(arr->Item(0), aOps);
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float rhs = aOps.ComputeNumber(arr->Item(1));
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return aOps.MergeMultiplicativeR(CalcOps::GetUnit(aValue), lhs, rhs);
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}
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default: {
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return aOps.ComputeLeafValue(aValue);
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}
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}
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}
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/**
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* The input unit operation for input_type being nsCSSValue.
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*/
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struct CSSValueInputCalcOps
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{
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typedef nsCSSValue input_type;
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typedef nsCSSValue::Array input_array_type;
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static nsCSSUnit GetUnit(const nsCSSValue& aValue)
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{
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return aValue.GetUnit();
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}
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};
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/**
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* Basic*CalcOps provide a partial implementation of the CalcOps
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* template parameter to ComputeCalc, for those callers whose merging
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* just consists of mathematics (rather than tree construction).
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*/
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struct BasicCoordCalcOps
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{
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typedef nscoord result_type;
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result_type
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MergeAdditive(nsCSSUnit aCalcFunction,
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result_type aValue1, result_type aValue2)
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{
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if (aCalcFunction == eCSSUnit_Calc_Plus) {
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return NSCoordSaturatingAdd(aValue1, aValue2);
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}
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MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Minus,
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"unexpected unit");
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return NSCoordSaturatingSubtract(aValue1, aValue2, 0);
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}
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result_type
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MergeMultiplicativeL(nsCSSUnit aCalcFunction,
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float aValue1, result_type aValue2)
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{
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MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Times_L,
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"unexpected unit");
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return NSCoordSaturatingMultiply(aValue2, aValue1);
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}
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result_type
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MergeMultiplicativeR(nsCSSUnit aCalcFunction,
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result_type aValue1, float aValue2)
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{
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MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Times_R ||
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aCalcFunction == eCSSUnit_Calc_Divided,
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"unexpected unit");
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if (aCalcFunction == eCSSUnit_Calc_Divided) {
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aValue2 = 1.0f / aValue2;
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}
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return NSCoordSaturatingMultiply(aValue1, aValue2);
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}
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};
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struct BasicFloatCalcOps
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{
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typedef float result_type;
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result_type
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MergeAdditive(nsCSSUnit aCalcFunction,
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result_type aValue1, result_type aValue2)
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{
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if (aCalcFunction == eCSSUnit_Calc_Plus) {
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return aValue1 + aValue2;
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}
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MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Minus,
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"unexpected unit");
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return aValue1 - aValue2;
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}
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result_type
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MergeMultiplicativeL(nsCSSUnit aCalcFunction,
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float aValue1, result_type aValue2)
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{
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MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Times_L,
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"unexpected unit");
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return aValue1 * aValue2;
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}
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result_type
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MergeMultiplicativeR(nsCSSUnit aCalcFunction,
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result_type aValue1, float aValue2)
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{
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if (aCalcFunction == eCSSUnit_Calc_Times_R) {
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return aValue1 * aValue2;
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}
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MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Divided,
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"unexpected unit");
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return aValue1 / aValue2;
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}
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};
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/**
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* A ComputeNumber implementation for callers that can assume numbers
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* are already normalized (i.e., anything past the parser).
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*/
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struct NumbersAlreadyNormalizedOps : public CSSValueInputCalcOps
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{
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float ComputeNumber(const nsCSSValue& aValue)
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{
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MOZ_ASSERT(aValue.GetUnit() == eCSSUnit_Number, "unexpected unit");
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return aValue.GetFloatValue();
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}
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};
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/**
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* SerializeCalc appends the serialization of aValue to a string.
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*
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* It is templatized over a CalcOps class that is expected to provide:
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*
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* // input_type and input_array_type have a bunch of very specific
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* // expectations (which happen to be met by two classes (nsCSSValue
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* // and nsStyleCoord). There must be methods (roughly):
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* // input_array_type* input_type::GetArrayValue();
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* // uint32_t input_array_type::Count() const;
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* // input_type& input_array_type::Item(uint32_t);
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* typedef ... input_type;
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* typedef ... input_array_type;
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*
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* static nsCSSUnit GetUnit(const input_type& aValue);
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*
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* void Append(const char* aString);
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* void AppendLeafValue(const input_type& aValue);
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* void AppendNumber(const input_type& aValue);
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*
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* Data structures given may or may not have a toplevel eCSSUnit_Calc
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* node representing a calc whose toplevel is not min() or max().
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*/
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template <class CalcOps>
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static void
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SerializeCalcInternal(const typename CalcOps::input_type& aValue, CalcOps &aOps);
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// Serialize the toplevel value in a calc() tree. See big comment
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// above.
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template <class CalcOps>
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static void
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SerializeCalc(const typename CalcOps::input_type& aValue, CalcOps &aOps)
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{
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aOps.Append("calc(");
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nsCSSUnit unit = CalcOps::GetUnit(aValue);
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if (unit == eCSSUnit_Calc) {
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const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
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MOZ_ASSERT(array->Count() == 1, "unexpected length");
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SerializeCalcInternal(array->Item(0), aOps);
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} else {
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SerializeCalcInternal(aValue, aOps);
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}
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aOps.Append(")");
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}
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static inline bool
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IsCalcAdditiveUnit(nsCSSUnit aUnit)
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{
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return aUnit == eCSSUnit_Calc_Plus ||
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aUnit == eCSSUnit_Calc_Minus;
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}
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static inline bool
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IsCalcMultiplicativeUnit(nsCSSUnit aUnit)
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{
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return aUnit == eCSSUnit_Calc_Times_L ||
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aUnit == eCSSUnit_Calc_Times_R ||
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aUnit == eCSSUnit_Calc_Divided;
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}
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// Serialize a non-toplevel value in a calc() tree. See big comment
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// above.
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template <class CalcOps>
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/* static */ void
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SerializeCalcInternal(const typename CalcOps::input_type& aValue, CalcOps &aOps)
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{
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nsCSSUnit unit = CalcOps::GetUnit(aValue);
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if (IsCalcAdditiveUnit(unit)) {
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const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
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MOZ_ASSERT(array->Count() == 2, "unexpected length");
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SerializeCalcInternal(array->Item(0), aOps);
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if (eCSSUnit_Calc_Plus == unit) {
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aOps.Append(" + ");
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} else {
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MOZ_ASSERT(eCSSUnit_Calc_Minus == unit, "unexpected unit");
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aOps.Append(" - ");
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}
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bool needParens = IsCalcAdditiveUnit(CalcOps::GetUnit(array->Item(1)));
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if (needParens) {
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aOps.Append("(");
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}
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SerializeCalcInternal(array->Item(1), aOps);
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if (needParens) {
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aOps.Append(")");
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}
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} else if (IsCalcMultiplicativeUnit(unit)) {
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const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
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MOZ_ASSERT(array->Count() == 2, "unexpected length");
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bool needParens = IsCalcAdditiveUnit(CalcOps::GetUnit(array->Item(0)));
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if (needParens) {
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aOps.Append("(");
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}
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if (unit == eCSSUnit_Calc_Times_L) {
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aOps.AppendNumber(array->Item(0));
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} else {
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SerializeCalcInternal(array->Item(0), aOps);
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}
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if (needParens) {
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aOps.Append(")");
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}
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if (eCSSUnit_Calc_Times_L == unit || eCSSUnit_Calc_Times_R == unit) {
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aOps.Append(" * ");
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} else {
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MOZ_ASSERT(eCSSUnit_Calc_Divided == unit, "unexpected unit");
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aOps.Append(" / ");
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}
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nsCSSUnit subUnit = CalcOps::GetUnit(array->Item(1));
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needParens = IsCalcAdditiveUnit(subUnit) ||
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IsCalcMultiplicativeUnit(subUnit);
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if (needParens) {
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aOps.Append("(");
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}
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if (unit == eCSSUnit_Calc_Times_L) {
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SerializeCalcInternal(array->Item(1), aOps);
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} else {
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aOps.AppendNumber(array->Item(1));
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}
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if (needParens) {
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aOps.Append(")");
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}
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} else {
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aOps.AppendLeafValue(aValue);
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}
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}
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} // namespace css
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} // namespace mozilla
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#endif /* !defined(CSSCalc_h_) */
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