Added mangleString member and onBefore*, onAfter* functions to GrGLFragmentShaderBuilder

BUILDS! Added mangleString, onBefore, and onAfterChildProcEmitCode() to GrGLFragmentShaderBuilder.cpp

BUG=skia:4182

Review URL: https://codereview.chromium.org/1288723002

include/core/SkString.h

@@ -39,6 +39,12 @@ static int SkStrFind(const char string[], const char substring[]) {
     return SkToS32(first - &string[0]);
 }
 
+static int SkStrFindLastOf(const char string[], const char subchar) {
+    const char* last = strrchr(string, subchar);
+    if (NULL == last) return -1;
+    return SkToS32(last - &string[0]);
+}
+
 static bool SkStrContains(const char string[], const char substring[]) {
     SkASSERT(string);
     SkASSERT(substring);
@@ -152,6 +158,9 @@ public:
     int find(const char substring[]) const {
         return SkStrFind(fRec->data(), substring);
     }
+    int findLastOf(const char subchar) const {
+        return SkStrFindLastOf(fRec->data(), subchar);
+    }
 
     friend bool operator==(const SkString& a, const SkString& b) {
         return a.equals(b);

src/gpu/GrProcessor.cpp

@@ -150,8 +150,9 @@ int GrFragmentProcessor::registerChildProcessor(const GrFragmentProcessor* child
     int index = fChildProcessors.count();
     fChildProcessors.push_back(GrFragmentStage(child));
 
-    if (child->willReadFragmentPosition())
+    if (child->willReadFragmentPosition()) {
         this->setWillReadFragmentPosition();
+    }
 
     return index;
 }

src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp

@@ -300,3 +300,15 @@ void GrGLFragmentShaderBuilder::addVarying(GrGLVarying* v, GrSLPrecision fsPrec)
     }
     fInputs.push_back().set(v->fType, GrGLShaderVar::kVaryingIn_TypeModifier, v->fFsIn, fsPrec);
 }
+
+void GrGLFragmentBuilder::onBeforeChildProcEmitCode() {
+    fSubstageIndices.back()++;
+    fSubstageIndices.push_back(0);
+    fMangleString.append(this->getMangleStringThisLevel());
+}
+
+void GrGLFragmentBuilder::onAfterChildProcEmitCode() {
+    fSubstageIndices.pop_back();
+    int removeAt = fMangleString.findLastOf('_');
+    fMangleString.remove(removeAt, fMangleString.size() - removeAt);
+}

src/gpu/gl/builders/GrGLFragmentShaderBuilder.h

@@ -17,7 +17,10 @@ class GrGLVarying;
  */
 class GrGLFragmentBuilder : public GrGLShaderBuilder {
 public:
-    GrGLFragmentBuilder(GrGLProgramBuilder* program) : INHERITED(program) {}
+    GrGLFragmentBuilder(GrGLProgramBuilder* program)
+        : INHERITED(program) {
+        fSubstageIndices.push_back(0);
+    }
     virtual ~GrGLFragmentBuilder() {}
     /**
      * Use of these features may require a GLSL extension to be enabled. Shaders may not compile
@@ -47,7 +50,54 @@ public:
         is in device space (e.g. 0,0 is the top left and pixel centers are at half-integers). */
     virtual const char* fragmentPosition() = 0;
 
+    /**
+     * Fragment procs with child procs should call these functions before/after calling emitCode
+     * on a child proc.
+     */
+    void onBeforeChildProcEmitCode();
+    void onAfterChildProcEmitCode();
+
+    int getChildNumberThisLevel() const {
+        if (fSubstageIndices.count() > 1) {
+            // second-to-last value in the fSubstageIndices stack is the index of the child proc
+            // at that level which is currently emitting code.
+            return fSubstageIndices[fSubstageIndices.count() - 2];
+        }
+        return -1;
+    }
+
+    const SkString& getMangleString() const { return fMangleString; }
+
+    SkString getMangleStringThisLevel() const {
+        SkString ret;
+        int childNumber = this->getChildNumberThisLevel();
+        if (childNumber >= 0) {
+            ret.printf("_c%d", childNumber);
+        }
+        return ret;
+    }
+
 private:
+    /*
+     * State that tracks which child proc in the proc tree is currently emitting code.  This is
+     * used to update the fMangleString, which is used to mangle the names of uniforms and functions
+     * emitted by the proc.  fSubstageIndices is a stack: its count indicates how many levels deep
+     * we are in the tree, and its second-to-last value is the index of the child proc at that
+     * level which is currently emitting code. For example, if fSubstageIndices = [3, 1, 2, 0], that
+     * means we're currently emitting code for the base proc's 3rd child's 1st child's 2nd child.
+     */
+    SkTArray<int> fSubstageIndices;
+
+    /*
+     * The mangle string is used to mangle the names of uniforms/functions emitted by the child
+     * procs so no duplicate uniforms/functions appear in the generated shader program. The mangle
+     * string is simply based on fSubstageIndices. For example, if fSubstageIndices = [3, 1, 2, 0],
+     * then the manglestring will be "_c3_c1_c2", and any uniform/function emitted by that proc will
+     * have "_c3_c1_c2" appended to its name, which can be interpreted as "base proc's 3rd child's
+     * 1st child's 2nd child".
+     */
+    SkString fMangleString;
+
     friend class GrGLPathProcessor;
 
     typedef GrGLShaderBuilder INHERITED;