1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/style/CSSCalc.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,361 @@
1.4 +/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +#ifndef CSSCalc_h_
1.9 +#define CSSCalc_h_
1.10 +
1.11 +#include "nsCSSValue.h"
1.12 +#include "nsStyleCoord.h"
1.13 +#include <math.h>
1.14 +
1.15 +namespace mozilla {
1.16 +
1.17 +namespace css {
1.18 +
1.19 +/**
1.20 + * ComputeCalc computes the result of a calc() expression tree.
1.21 + *
1.22 + * It is templatized over a CalcOps class that is expected to provide:
1.23 + *
1.24 + * // input_type and input_array_type have a bunch of very specific
1.25 + * // expectations (which happen to be met by two classes (nsCSSValue
1.26 + * // and nsStyleCoord). There must be methods (roughly):
1.27 + * // input_array_type* input_type::GetArrayValue();
1.28 + * // uint32_t input_array_type::Count() const;
1.29 + * // input_type& input_array_type::Item(uint32_t);
1.30 + * typedef ... input_type;
1.31 + * typedef ... input_array_type;
1.32 + *
1.33 + * typedef ... result_type;
1.34 + *
1.35 + * // GetUnit(avalue) must return the correct nsCSSUnit for any
1.36 + * // value that represents a calc tree node (eCSSUnit_Calc*). For
1.37 + * // other nodes, it may return any non eCSSUnit_Calc* unit.
1.38 + * static nsCSSUnit GetUnit(const input_type& aValue);
1.39 + *
1.40 + * result_type
1.41 + * MergeAdditive(nsCSSUnit aCalcFunction,
1.42 + * result_type aValue1, result_type aValue2);
1.43 + *
1.44 + * result_type
1.45 + * MergeMultiplicativeL(nsCSSUnit aCalcFunction,
1.46 + * float aValue1, result_type aValue2);
1.47 + *
1.48 + * result_type
1.49 + * MergeMultiplicativeR(nsCSSUnit aCalcFunction,
1.50 + * result_type aValue1, float aValue2);
1.51 + *
1.52 + * result_type
1.53 + * ComputeLeafValue(const input_type& aValue);
1.54 + *
1.55 + * float
1.56 + * ComputeNumber(const input_type& aValue);
1.57 + *
1.58 + * The CalcOps methods might compute the calc() expression down to a
1.59 + * number, reduce some parts of it to a number but replicate other
1.60 + * parts, or produce a tree with a different data structure (for
1.61 + * example, nsCSS* for specified values vs nsStyle* for computed
1.62 + * values).
1.63 + *
1.64 + * For each leaf in the calc() expression, ComputeCalc will call either
1.65 + * ComputeNumber (when the leaf is the left side of a Times_L or the
1.66 + * right side of a Times_R or Divided) or ComputeLeafValue (otherwise).
1.67 + * (The CalcOps in the CSS parser that reduces purely numeric
1.68 + * expressions in turn calls ComputeCalc on numbers; other ops can
1.69 + * presume that expressions in the number positions have already been
1.70 + * normalized to a single numeric value and derive from
1.71 + * NumbersAlreadyNormalizedCalcOps.)
1.72 + *
1.73 + * For non-leaves, one of the Merge functions will be called:
1.74 + * MergeAdditive for Plus and Minus
1.75 + * MergeMultiplicativeL for Times_L (number * value)
1.76 + * MergeMultiplicativeR for Times_R (value * number) and Divided
1.77 + */
1.78 +template <class CalcOps>
1.79 +static typename CalcOps::result_type
1.80 +ComputeCalc(const typename CalcOps::input_type& aValue, CalcOps &aOps)
1.81 +{
1.82 + switch (CalcOps::GetUnit(aValue)) {
1.83 + case eCSSUnit_Calc: {
1.84 + typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
1.85 + NS_ABORT_IF_FALSE(arr->Count() == 1, "unexpected length");
1.86 + return ComputeCalc(arr->Item(0), aOps);
1.87 + }
1.88 + case eCSSUnit_Calc_Plus:
1.89 + case eCSSUnit_Calc_Minus: {
1.90 + typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
1.91 + NS_ABORT_IF_FALSE(arr->Count() == 2, "unexpected length");
1.92 + typename CalcOps::result_type lhs = ComputeCalc(arr->Item(0), aOps),
1.93 + rhs = ComputeCalc(arr->Item(1), aOps);
1.94 + return aOps.MergeAdditive(CalcOps::GetUnit(aValue), lhs, rhs);
1.95 + }
1.96 + case eCSSUnit_Calc_Times_L: {
1.97 + typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
1.98 + NS_ABORT_IF_FALSE(arr->Count() == 2, "unexpected length");
1.99 + float lhs = aOps.ComputeNumber(arr->Item(0));
1.100 + typename CalcOps::result_type rhs = ComputeCalc(arr->Item(1), aOps);
1.101 + return aOps.MergeMultiplicativeL(CalcOps::GetUnit(aValue), lhs, rhs);
1.102 + }
1.103 + case eCSSUnit_Calc_Times_R:
1.104 + case eCSSUnit_Calc_Divided: {
1.105 + typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
1.106 + NS_ABORT_IF_FALSE(arr->Count() == 2, "unexpected length");
1.107 + typename CalcOps::result_type lhs = ComputeCalc(arr->Item(0), aOps);
1.108 + float rhs = aOps.ComputeNumber(arr->Item(1));
1.109 + return aOps.MergeMultiplicativeR(CalcOps::GetUnit(aValue), lhs, rhs);
1.110 + }
1.111 + default: {
1.112 + return aOps.ComputeLeafValue(aValue);
1.113 + }
1.114 + }
1.115 +}
1.116 +
1.117 +/**
1.118 + * The input unit operation for input_type being nsCSSValue.
1.119 + */
1.120 +struct CSSValueInputCalcOps
1.121 +{
1.122 + typedef nsCSSValue input_type;
1.123 + typedef nsCSSValue::Array input_array_type;
1.124 +
1.125 + static nsCSSUnit GetUnit(const nsCSSValue& aValue)
1.126 + {
1.127 + return aValue.GetUnit();
1.128 + }
1.129 +
1.130 +};
1.131 +
1.132 +/**
1.133 + * Basic*CalcOps provide a partial implementation of the CalcOps
1.134 + * template parameter to ComputeCalc, for those callers whose merging
1.135 + * just consists of mathematics (rather than tree construction).
1.136 + */
1.137 +
1.138 +struct BasicCoordCalcOps
1.139 +{
1.140 + typedef nscoord result_type;
1.141 +
1.142 + result_type
1.143 + MergeAdditive(nsCSSUnit aCalcFunction,
1.144 + result_type aValue1, result_type aValue2)
1.145 + {
1.146 + if (aCalcFunction == eCSSUnit_Calc_Plus) {
1.147 + return NSCoordSaturatingAdd(aValue1, aValue2);
1.148 + }
1.149 + NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Minus,
1.150 + "unexpected unit");
1.151 + return NSCoordSaturatingSubtract(aValue1, aValue2, 0);
1.152 + }
1.153 +
1.154 + result_type
1.155 + MergeMultiplicativeL(nsCSSUnit aCalcFunction,
1.156 + float aValue1, result_type aValue2)
1.157 + {
1.158 + NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_L,
1.159 + "unexpected unit");
1.160 + return NSCoordSaturatingMultiply(aValue2, aValue1);
1.161 + }
1.162 +
1.163 + result_type
1.164 + MergeMultiplicativeR(nsCSSUnit aCalcFunction,
1.165 + result_type aValue1, float aValue2)
1.166 + {
1.167 + NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_R ||
1.168 + aCalcFunction == eCSSUnit_Calc_Divided,
1.169 + "unexpected unit");
1.170 + if (aCalcFunction == eCSSUnit_Calc_Divided) {
1.171 + aValue2 = 1.0f / aValue2;
1.172 + }
1.173 + return NSCoordSaturatingMultiply(aValue1, aValue2);
1.174 + }
1.175 +};
1.176 +
1.177 +struct BasicFloatCalcOps
1.178 +{
1.179 + typedef float result_type;
1.180 +
1.181 + result_type
1.182 + MergeAdditive(nsCSSUnit aCalcFunction,
1.183 + result_type aValue1, result_type aValue2)
1.184 + {
1.185 + if (aCalcFunction == eCSSUnit_Calc_Plus) {
1.186 + return aValue1 + aValue2;
1.187 + }
1.188 + NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Minus,
1.189 + "unexpected unit");
1.190 + return aValue1 - aValue2;
1.191 + }
1.192 +
1.193 + result_type
1.194 + MergeMultiplicativeL(nsCSSUnit aCalcFunction,
1.195 + float aValue1, result_type aValue2)
1.196 + {
1.197 + NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_L,
1.198 + "unexpected unit");
1.199 + return aValue1 * aValue2;
1.200 + }
1.201 +
1.202 + result_type
1.203 + MergeMultiplicativeR(nsCSSUnit aCalcFunction,
1.204 + result_type aValue1, float aValue2)
1.205 + {
1.206 + if (aCalcFunction == eCSSUnit_Calc_Times_R) {
1.207 + return aValue1 * aValue2;
1.208 + }
1.209 + NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Divided,
1.210 + "unexpected unit");
1.211 + return aValue1 / aValue2;
1.212 + }
1.213 +};
1.214 +
1.215 +/**
1.216 + * A ComputeNumber implementation for callers that can assume numbers
1.217 + * are already normalized (i.e., anything past the parser).
1.218 + */
1.219 +struct NumbersAlreadyNormalizedOps : public CSSValueInputCalcOps
1.220 +{
1.221 + float ComputeNumber(const nsCSSValue& aValue)
1.222 + {
1.223 + NS_ABORT_IF_FALSE(aValue.GetUnit() == eCSSUnit_Number, "unexpected unit");
1.224 + return aValue.GetFloatValue();
1.225 + }
1.226 +};
1.227 +
1.228 +/**
1.229 + * SerializeCalc appends the serialization of aValue to a string.
1.230 + *
1.231 + * It is templatized over a CalcOps class that is expected to provide:
1.232 + *
1.233 + * // input_type and input_array_type have a bunch of very specific
1.234 + * // expectations (which happen to be met by two classes (nsCSSValue
1.235 + * // and nsStyleCoord). There must be methods (roughly):
1.236 + * // input_array_type* input_type::GetArrayValue();
1.237 + * // uint32_t input_array_type::Count() const;
1.238 + * // input_type& input_array_type::Item(uint32_t);
1.239 + * typedef ... input_type;
1.240 + * typedef ... input_array_type;
1.241 + *
1.242 + * static nsCSSUnit GetUnit(const input_type& aValue);
1.243 + *
1.244 + * void Append(const char* aString);
1.245 + * void AppendLeafValue(const input_type& aValue);
1.246 + * void AppendNumber(const input_type& aValue);
1.247 + *
1.248 + * Data structures given may or may not have a toplevel eCSSUnit_Calc
1.249 + * node representing a calc whose toplevel is not min() or max().
1.250 + */
1.251 +
1.252 +template <class CalcOps>
1.253 +static void
1.254 +SerializeCalcInternal(const typename CalcOps::input_type& aValue, CalcOps &aOps);
1.255 +
1.256 +// Serialize the toplevel value in a calc() tree. See big comment
1.257 +// above.
1.258 +template <class CalcOps>
1.259 +static void
1.260 +SerializeCalc(const typename CalcOps::input_type& aValue, CalcOps &aOps)
1.261 +{
1.262 + aOps.Append("calc(");
1.263 + nsCSSUnit unit = CalcOps::GetUnit(aValue);
1.264 + if (unit == eCSSUnit_Calc) {
1.265 + const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
1.266 + NS_ABORT_IF_FALSE(array->Count() == 1, "unexpected length");
1.267 + SerializeCalcInternal(array->Item(0), aOps);
1.268 + } else {
1.269 + SerializeCalcInternal(aValue, aOps);
1.270 + }
1.271 + aOps.Append(")");
1.272 +}
1.273 +
1.274 +static inline bool
1.275 +IsCalcAdditiveUnit(nsCSSUnit aUnit)
1.276 +{
1.277 + return aUnit == eCSSUnit_Calc_Plus ||
1.278 + aUnit == eCSSUnit_Calc_Minus;
1.279 +}
1.280 +
1.281 +static inline bool
1.282 +IsCalcMultiplicativeUnit(nsCSSUnit aUnit)
1.283 +{
1.284 + return aUnit == eCSSUnit_Calc_Times_L ||
1.285 + aUnit == eCSSUnit_Calc_Times_R ||
1.286 + aUnit == eCSSUnit_Calc_Divided;
1.287 +}
1.288 +
1.289 +// Serialize a non-toplevel value in a calc() tree. See big comment
1.290 +// above.
1.291 +template <class CalcOps>
1.292 +/* static */ void
1.293 +SerializeCalcInternal(const typename CalcOps::input_type& aValue, CalcOps &aOps)
1.294 +{
1.295 + nsCSSUnit unit = CalcOps::GetUnit(aValue);
1.296 + if (IsCalcAdditiveUnit(unit)) {
1.297 + const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
1.298 + NS_ABORT_IF_FALSE(array->Count() == 2, "unexpected length");
1.299 +
1.300 + SerializeCalcInternal(array->Item(0), aOps);
1.301 +
1.302 + if (eCSSUnit_Calc_Plus == unit) {
1.303 + aOps.Append(" + ");
1.304 + } else {
1.305 + NS_ABORT_IF_FALSE(eCSSUnit_Calc_Minus == unit, "unexpected unit");
1.306 + aOps.Append(" - ");
1.307 + }
1.308 +
1.309 + bool needParens = IsCalcAdditiveUnit(CalcOps::GetUnit(array->Item(1)));
1.310 + if (needParens) {
1.311 + aOps.Append("(");
1.312 + }
1.313 + SerializeCalcInternal(array->Item(1), aOps);
1.314 + if (needParens) {
1.315 + aOps.Append(")");
1.316 + }
1.317 + } else if (IsCalcMultiplicativeUnit(unit)) {
1.318 + const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
1.319 + NS_ABORT_IF_FALSE(array->Count() == 2, "unexpected length");
1.320 +
1.321 + bool needParens = IsCalcAdditiveUnit(CalcOps::GetUnit(array->Item(0)));
1.322 + if (needParens) {
1.323 + aOps.Append("(");
1.324 + }
1.325 + if (unit == eCSSUnit_Calc_Times_L) {
1.326 + aOps.AppendNumber(array->Item(0));
1.327 + } else {
1.328 + SerializeCalcInternal(array->Item(0), aOps);
1.329 + }
1.330 + if (needParens) {
1.331 + aOps.Append(")");
1.332 + }
1.333 +
1.334 + if (eCSSUnit_Calc_Times_L == unit || eCSSUnit_Calc_Times_R == unit) {
1.335 + aOps.Append(" * ");
1.336 + } else {
1.337 + NS_ABORT_IF_FALSE(eCSSUnit_Calc_Divided == unit, "unexpected unit");
1.338 + aOps.Append(" / ");
1.339 + }
1.340 +
1.341 + nsCSSUnit subUnit = CalcOps::GetUnit(array->Item(1));
1.342 + needParens = IsCalcAdditiveUnit(subUnit) ||
1.343 + IsCalcMultiplicativeUnit(subUnit);
1.344 + if (needParens) {
1.345 + aOps.Append("(");
1.346 + }
1.347 + if (unit == eCSSUnit_Calc_Times_L) {
1.348 + SerializeCalcInternal(array->Item(1), aOps);
1.349 + } else {
1.350 + aOps.AppendNumber(array->Item(1));
1.351 + }
1.352 + if (needParens) {
1.353 + aOps.Append(")");
1.354 + }
1.355 + } else {
1.356 + aOps.AppendLeafValue(aValue);
1.357 + }
1.358 +}
1.359 +
1.360 +}
1.361 +
1.362 +}
1.363 +
1.364 +#endif /* !defined(CSSCalc_h_) */
