Added handling of 'const' type qualifier keyword

There is currently no enforcement of a variable being constant, and the
actual type is the same as if 'const' wasn't present.

c-tests/types.c

@@ -9,7 +9,10 @@ unsigned long f;
 unsigned long int g;
 
 volatile int i;
-int volatile j;
+int volatile static j;
+
+const int x;
+long const y;
 
 int main(void) {
 	return 0;

interpreter.h

@@ -177,7 +177,8 @@ enum LexToken {
                TokenBackSlash,
                TokenVolatileType,
                TokenHashPragma,
-               TokenUnderscorePragma
+               TokenUnderscorePragma,
+               TokenConstType
 };
 
 /* used in dynamic memory allocation */

lex.c

@@ -96,7 +96,8 @@ static struct ReservedWord ReservedWords[] = {
     {"while", TokenWhile},
     {"volatile", TokenVolatileType},
     {"#pragma", TokenHashPragma},
-    {"_Pragma", TokenUnderscorePragma}
+    {"_Pragma", TokenUnderscorePragma},
+    {"const", TokenConstType}
 };
 
 
@@ -851,7 +852,7 @@ enum LexToken LexGetRawToken(struct ParseState *Parser, struct Value **Value,
 #ifdef DEBUG_LEXER
     printf("Got token=%02x inc=%d pos=%d\n", Token, IncPos, Parser->CharacterPos);
 #endif
-    assert(Token >= TokenNone && Token <= TokenUnderscorePragma);
+    assert(Token >= TokenNone && Token <= TokenConstType);
     return Token;
 }
 

parse.c

@@ -748,6 +748,7 @@ enum ParseResult ParseStatement(struct ParseState *Parser,
     case TokenRegisterType:
     case TokenExternType:
     case TokenVolatileType:
+    case TokenConstType:
         *Parser = PreState;
         CheckTrailingSemicolon = ParseDeclaration(Parser, Token);
         break;

stats.c

@@ -114,7 +114,8 @@ struct LexTokenStat LexTokenStats[NO_TOKENS] = {
         {"TokenBackSlash", {0, 0, 0, 0, 0, 0, 0}},
         {"TokenVolatileType", {0, 0, 0, 0, 0, 0, 0}},
         {"TokenHashPragma", {0, 0, 0, 0, 0, 0, 0}},
-        {"TokenUnderscorePragma", {0, 0, 0, 0, 0, 0, 0}}
+        {"TokenUnderscorePragma", {0, 0, 0, 0, 0, 0, 0}},
+        {"TokenConstType", {0, 0, 0, 0, 0, 0, 0}}
 };
 
 

stats.h

@@ -8,7 +8,7 @@
 #include "interpreter.h"
 
 #define NO_RUN_MODES 7
-#define NO_TOKENS 100
+#define NO_TOKENS 101
 
 extern const char *RunModeNames[NO_RUN_MODES];
 

type.c

@@ -411,7 +411,7 @@ int TypeParseFront(struct ParseState *Parser, struct ValueType **Typ,
     /* handle any leading type qualifiers/storage classes */
     while (Token == TokenStaticType || Token == TokenAutoType ||
             Token == TokenRegisterType || Token == TokenExternType ||
-            Token == TokenVolatileType) {
+            Token == TokenVolatileType || Token == TokenConstType) {
         if (Token == TokenStaticType)
             StaticQualifier = true;
         else if (Token == TokenVolatileType)
@@ -424,7 +424,7 @@ int TypeParseFront(struct ParseState *Parser, struct ValueType **Typ,
     enum LexToken FollowToken = LexGetToken(Parser, &LexerValue, false);
     while (FollowToken == TokenStaticType || FollowToken == TokenAutoType ||
             FollowToken == TokenRegisterType || FollowToken == TokenExternType ||
-            FollowToken == TokenVolatileType) {
+            FollowToken == TokenVolatileType || FollowToken == TokenConstType) {
         if (FollowToken == TokenStaticType)
             StaticQualifier = true;
         else if (FollowToken == TokenVolatileType)