Allow swizzles to begin with a constant value.

CMakeLists.txt

@@ -270,7 +270,7 @@ TESTSUITE ( and-or-not-synonyms aastep arithmetic array array-derivs array-range
             oslc-err-noreturn oslc-err-notfunc
             oslc-err-outputparamvararray oslc-err-paramdefault
             oslc-err-struct-array-init oslc-err-struct-ctr
-            oslc-err-struct-dup
+            oslc-err-struct-dup oslc-err-swizzle
             oslc-warn-commainit
             oslc-variadic-macro
             oslc-version

src/liboslcomp/ast.cpp

@@ -779,9 +779,9 @@ ASTswizzle::print (std::ostream &out, int indentlevel) const
 
 
 ASTNode* ASTfieldselect::create (OSLCompilerImpl *comp, ASTNode *expr,
-                                 ustring field)
+                                 ustring field, bool swizzle)
 {
-    if (expr->typespec().is_structure_based())
+    if (!swizzle && expr->typespec().is_structure_based())
         return new ASTstructselect (comp, expr, field);
 
     const TypeSpec &type = expr->nodetype() != structselect_node ? expr->typespec() :
@@ -797,13 +797,16 @@ ASTNode* ASTfieldselect::create (OSLCompilerImpl *comp, ASTNode *expr,
         int indexes[3];
         switch (ASTswizzle::indices (field, indexes, 3, true)) {
             case 1: {
+                // c.0 && c.1 not allowed
+                ASSERT (indexes[0] >= 0);
                 if (!index)
                     return new ASTindex (comp, expr, new ASTliteral (comp, indexes[0]));
                 index->extend(new ASTliteral (comp, indexes[0]));
                 return index;
             }
 
             case 3: {
+                bool allconst = true;
                 // Don't leak soon to be unused expr node
                 std::unique_ptr<ASTNode> cleanup(index);
                 ASTNode* index0 = nullptr;
@@ -815,6 +818,7 @@ ASTNode* ASTfieldselect::create (OSLCompilerImpl *comp, ASTNode *expr,
                 ASTNode *args[3];
                 for (int i = 0; i < 3; ++i) {
                     if (indexes[i] >= 0) {
+                        allconst = false;
                         args[i] = new ASTliteral (comp, indexes[i]);
                         if (i == 0 && index) {
                             // Re-use expr by extending the ASTindex.
@@ -832,6 +836,14 @@ ASTNode* ASTfieldselect::create (OSLCompilerImpl *comp, ASTNode *expr,
                 }
                 args[0]->append (args[1]);
                 args[1]->append (args[2]);
+
+                if (allconst) {
+                    // return a type constructor instead of a swizzle
+                    ASSERT (!cleanup);
+                    // initial expression will be unused
+                    cleanup.reset (expr);
+                    return new ASTtype_constructor (comp, type, args[0]);
+                }
                 return new ASTswizzle (comp, args[0], field);
             }
 

src/liboslcomp/ast.h

@@ -605,7 +605,8 @@ class ASTfieldselect : public ASTNode
     ustring m_fullname;       ///< Full name of variable and field
 
 public:
-    static ASTNode* create (OSLCompilerImpl *comp, ASTNode *expr, ustring field);
+    static ASTNode* create (OSLCompilerImpl *comp, ASTNode *expr, ustring field,
+                            bool swizzle = false);
 
     ustring field () const { return m_field; }
     ustring fullname () const { return m_fullname; }

src/liboslcomp/oslgram.y

@@ -83,7 +83,7 @@ static std::stack<TypeSpec> typespec_stack; // just for function_declaration
 
 
 // Define the terminal symbols.
-%token <s> IDENTIFIER STRING_LITERAL
+%token <s> IDENTIFIER STRING_LITERAL SWIZZLE_IDENTIFIER
 %token <i> INT_LITERAL
 %token <f> FLOAT_LITERAL
 %token <i> COLORTYPE FLOATTYPE INTTYPE MATRIXTYPE 
@@ -769,6 +769,10 @@ id_or_field
                 {
                     $$ = new ASTvariable_ref (oslcompiler, ustring($1));
                 }
+        | variable_lvalue SWIZZLE_IDENTIFIER
+                {
+                    $$ = ASTfieldselect::create (oslcompiler, $1, ustring($2));
+                }
         | variable_lvalue '.' IDENTIFIER
                 {
                     $$ = ASTfieldselect::create (oslcompiler, $1, ustring($3));

src/liboslcomp/osllex.l

@@ -80,6 +80,11 @@ STR     \"(\\.|[^\\"\n])*\"
         /* " This extra quote fixes emacs syntax highlighting on this file */
  /* Identifier: alphanumeric, may contain digits after the first character */
 IDENT           ({ALPHA}|[_])({ALPHA}|{DIGIT}|[_])*
+ /* Swizzle that starts with a constant value
+    Needs to include the . selector to take precedence over FLT */
+SWIZZLE         (\.[01][01rgbxyz]{2})
+
+
  /* C preprocessor (cpp) directives */
 CPP             ^[ \t]*#.*\n
 CPLUSCOMMENT    \/\/.*\n
@@ -196,6 +201,11 @@ void preprocess (const char *yytext);
                             SETLINE;
                             return IDENTIFIER;
                         }
+{SWIZZLE}               {
+                            yylval.s = ustring(yytext+1).c_str();
+                            SETLINE;
+                            return SWIZZLE_IDENTIFIER;
+                        }
 
  /* Literal values */
 {INTEGER}               {

testsuite/oslc-err-swizzle/ref/out.txt

@@ -0,0 +1,3 @@
+test.osl:7: error: Can't assign via = to something that isn't an lvalue
+test.osl:8: error: Can't assign via = to something that isn't an lvalue
+FAILED test.osl

testsuite/oslc-err-swizzle/run.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+# command = oslc("test.osl")
+# don't even need that -- it's automatic
+failureok = 1     # this test is expected to have oslc errors

testsuite/oslc-err-swizzle/test.osl

@@ -0,0 +1,10 @@
+// Error on invalid swizzle operations
+
+shader test ()
+{
+    color c;
+
+    c.rg0 = color(1);
+    c.01r = color(1);
+    // c.0;
+}

testsuite/swizzle/ref/out.txt

@@ -6,6 +6,8 @@ c.r00: 1 0 0
 c.g01: 2 0 1
 c.b11: 3 1 1
 c.bg1: 3 2 1
+c.01g: 0 1 2
+c.101: 1 0 1
 c.rgb = c.brg: 3 1 2
 c.rgb = c.brg: 2 3 1
 c.rgb = c.brg: 1 2 3

testsuite/swizzle/swizzle.osl

@@ -4,6 +4,10 @@
 
 shader swizzle ()
 {
+    // Make sure floats don't generate a swizzle operation.
+    float noswizzle = 1.101;
+    noswizzle = 1.001;
+
     color c = color(1,2,3);
     printf("c: %g\n", c);
 
@@ -19,6 +23,8 @@ shader swizzle ()
     printf("c.g01: %g\n", c.g01);
     printf("c.b11: %g\n", c.b11);
     printf("c.bg1: %g\n", c.bg1);
+    printf("c.01g: %g\n", c.01g);
+    printf("c.101: %g\n", c.101);
 
     c = c.brg;
     printf("c.rgb = c.brg: %g\n", c);