Preprocessor: 1) Rationalize the "fixed atom" scheme, 2) remove redundant lookups when the text is already available.

This simplification is a prelude to eliminating what I appear unnecessary
symbol inserts into tables when tokenizing in the preprecessor, which
show up as taking notable time. (Performance issue.)  It also simply makes
the preprocessor easier to understand, which it is badly in need of.

glslang/MachineIndependent/preprocessor/PpTokens.h

@@ -78,40 +78,89 @@ NVIDIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef PARSER_H
 #define PARSER_H
 
-#define CPP_AND_OP         257
-#define CPP_SUB_ASSIGN     259
-#define CPP_MOD_ASSIGN     260
-#define CPP_ADD_ASSIGN     261
-#define CPP_DIV_ASSIGN     262
-#define CPP_MUL_ASSIGN     263
-#define CPP_EQ_OP          264
-#define CPP_XOR_OP         265 
-#define CPP_ERROR_SY       266
-#define CPP_FLOATCONSTANT  267
-#define CPP_GE_OP          268
-#define CPP_RIGHT_OP       269
-#define CPP_IDENTIFIER     270
-#define CPP_INTCONSTANT    271
-#define CPP_LE_OP          272
-#define CPP_LEFT_OP        273
-#define CPP_DEC_OP         274
-#define CPP_NE_OP          275
-#define CPP_OR_OP          276
-#define CPP_INC_OP         277
-#define CPP_STRCONSTANT    278
-#define CPP_RIGHT_ASSIGN   280
-#define CPP_LEFT_ASSIGN    281
-#define CPP_AND_ASSIGN     282
-#define CPP_OR_ASSIGN      283
-#define CPP_XOR_ASSIGN     284
-#define CPP_LEFT_BRACKET   285
-#define CPP_RIGHT_BRACKET  286
-#define CPP_LEFT_BRACE     287
-#define CPP_RIGHT_BRACE    288
-#define CPP_UINTCONSTANT   289
-#define CPP_DOUBLECONSTANT 290
-#define CPP_TOKEN_PASTE    291
+namespace glslang {
 
-#define CPP_FIRST_USER_TOKEN_SY 292
+// Multi-character tokens
+enum EFixedAtoms {
+    PpAtomMaxSingle = 256, // single character tokens get their own char value as their token, skip them
+
+    // Operators
+
+    PpAtomAdd,
+    PpAtomSub,
+    PpAtomMul,
+    PpAtomDiv,
+    PpAtomMod,
+
+    PpAtomRight,
+    PpAtomLeft,
+
+    PpAtomRightAssign,
+    PpAtomLeftAssign,
+    PpAtomAndAssign,
+    PpAtomOrAssign,
+    PpAtomXorAssign,
+
+    PpAtomAnd,
+    PpAtomOr,
+    PpAtomXor,
+
+    PpAtomEQ,
+    PpAtomNE,
+    PpAtomGE,
+    PpAtomLE,
+
+    PpAtomDecrement,
+    PpAtomIncrement,
+
+    PpAtomPaste,
+
+    // Constants
+
+    PpAtomConstInt,
+    PpAtomConstUint,
+    PpAtomConstFloat,
+    PpAtomConstDouble,
+    PpAtomConstString,
+
+    // Indentifiers 
+    PpAtomIdentifier,
+
+    // preprocessor "keywords"
+
+    PpAtomDefine,
+    PpAtomDefined,
+    PpAtomUndef,
+
+    PpAtomIf,
+    PpAtomIfdef,
+    PpAtomIfndef,
+    PpAtomElse,
+    PpAtomElif,
+    PpAtomEndif,
+
+    PpAtomLine,
+    PpAtomPragma,
+    PpAtomError,
+
+    // #version ...
+    PpAtomVersion,
+    PpAtomCore,
+    PpAtomCompatibility,
+    PpAtomEs,
+
+    // #extension
+    PpAtomExtension,
+
+    // __LINE__, __FILE__, __VERSION__
+
+    PpAtomLineMacro,
+    PpAtomFileMacro,
+    PpAtomVersionMacro,
+
+    PpAtomLast,
+};
+
+} // end namespace glslang
 
 #endif /* not PARSER_H */