Local variables implemented

git-svn-id: http://picoc.googlecode.com/svn/trunk@18 21eae674-98b7-11dd-bd71-f92a316d2d60

parse.c

@@ -11,6 +11,10 @@ struct TableEntry GlobalHashTable[GLOBAL_TABLE_SIZE];
 struct LexState FunctionStore[FUNCTION_STORE_MAX];
 int FunctionStoreUsed = 0;
 
+/* the stack */
+struct StackFrame Stack[STACK_MAX];
+int StackUsed = 0;
+
 /* local prototypes */
 int ParseExpression(struct LexState *Lexer, struct Value *Result, int RunIt);
 void ParseIntExpression(struct LexState *Lexer, struct Value *Result, int RunIt);
@@ -20,7 +24,7 @@ int ParseStatement(struct LexState *Lexer, int RunIt);
 /* initialise the parser */
 void ParseInit()
 {
-    TableInit(&GlobalTable, &GlobalHashTable[0], "global", GLOBAL_TABLE_SIZE);
+    TableInit(&GlobalTable, &GlobalHashTable[0], GLOBAL_TABLE_SIZE);
 }
 
 /* define a variable */
@@ -30,19 +34,44 @@ void VariableDefine(struct LexState *Lexer, const Str *Ident, enum ValueType Typ
     
     memset(&NewValue, '\0', sizeof(NewValue));
     NewValue.Typ = Typ;
-    if (!TableSet(&GlobalTable, Ident, &NewValue))
+    
+    if (!TableSet((StackUsed == 0) ? &GlobalTable : &Stack[StackUsed-1].LocalTable, Ident, &NewValue))
         ProgramFail(Lexer, "'%S' is already defined", Ident);
 }
 
 /* get the value of a variable. must be defined */
 void VariableGet(struct LexState *Lexer, Str *Ident, struct Value *Val, struct Value **LVal)
 {
+    int Frame;
+    
+    for (Frame = StackUsed-1; Frame >= 0; Frame--)
+    {
+        if (TableGet(&Stack[Frame].LocalTable, Ident, LVal))
+        {
+            *Val = **LVal;
+            return;
+        }
+    }
+    
     if (!TableGet(&GlobalTable, Ident, LVal))
         ProgramFail(Lexer, "'%S' is undefined", Ident);
 
     *Val = **LVal;
 }
 
+/* add a stack frame when doing a function call */
+void StackFrameAdd(struct LexState *Lexer)
+{
+    struct StackFrame *NewFrame = &Stack[StackUsed];
+    
+    if (StackUsed >= STACK_MAX)
+        ProgramFail(Lexer, "too many nested function calls");
+        
+    NewFrame->ReturnLex = *Lexer;
+    TableInit(&NewFrame->LocalTable, &NewFrame->LocalHashTable[0], LOCAL_TABLE_SIZE);
+    StackUsed++;
+}
+
 /* parse a single value */
 int ParseValue(struct LexState *Lexer, struct Value *Result, struct Value **LValue, int RunIt)
 {

picoc.c

@@ -71,7 +71,6 @@ void ScanFile(const Str *FileName)
 int main(int argc, char **argv)
 {
     Str FileName;
-    Str StartFunc;
     
     if (argc < 2)
         Fail("Format: picoc <program.c> <args>...\n");

picoc.h

@@ -7,6 +7,8 @@
 #define USE_MALLOC
 #define GLOBAL_TABLE_SIZE 199               /* global variable table */
 #define FUNCTION_STORE_MAX 50               /* maximum number of used-defined functions */
+#define STACK_MAX 10                        /* maximum function call stack depth */
+#define LOCAL_TABLE_SIZE 11                 /* maximum number of local variables */
 #define LARGE_INT_POWER_OF_TEN 1000000000   /* the largest power of ten which fits in an int on this architecture */
 
 /* handy definitions */
@@ -128,7 +130,6 @@ struct TableEntry
     
 struct Table
 {
-    const char *Name;
     short Size;
     struct TableEntry *HashTable;
 };
@@ -142,6 +143,14 @@ struct LexState
     const Str *FileName;
 };
 
+/* stack frame for function calls */
+struct StackFrame
+{
+    struct LexState ReturnLex;          /* how we got here */
+    struct Table LocalTable;            /* the local variables and parameters */
+    struct TableEntry LocalHashTable[LOCAL_TABLE_SIZE];
+};
+
 
 /* str.c */
 void StrToC(char *Dest, int DestSize, const Str *Source);
@@ -157,7 +166,7 @@ void ProgramFail(struct LexState *Lexer, const char *Message, ...);
 void ScanFile(const Str *FileName);
 
 /* table.c */
-void TableInit(struct Table *Tbl, struct TableEntry *HashTable, const char *Name, int Size);
+void TableInit(struct Table *Tbl, struct TableEntry *HashTable, int Size);
 int TableSet(struct Table *Tbl, const Str *Key, struct Value *Val);
 int TableGet(struct Table *Tbl, const Str *Key, struct Value **Val);
 

table.c

@@ -1,8 +1,6 @@
 #include <string.h>
-
 #include "picoc.h"
-
-    
+ 
 static unsigned int TableHash(const Str *Key)
 {
     unsigned int Hash;
@@ -24,10 +22,8 @@ static unsigned int TableHash(const Str *Key)
     return Hash;
 }
 
-
-void TableInit(struct Table *Tbl, struct TableEntry *HashTable, const char *Name, int Size)
+void TableInit(struct Table *Tbl, struct TableEntry *HashTable, int Size)
 {
-    Tbl->Name = Name;
     Tbl->Size = Size;
     Tbl->HashTable = HashTable;
     memset(HashTable, '\0', sizeof(struct TableEntry) * Size);
@@ -48,7 +44,6 @@ static int TableCheckEntry(struct Table *Tbl, const Str *Key, int HashPos)
         return -2;  /* wrong key */
 }
 
-
 static int TableSearch(struct Table *Tbl, const Str *Key, int *AddAt)
 {
     int HashValue;
@@ -76,7 +71,6 @@ static int TableSearch(struct Table *Tbl, const Str *Key, int *AddAt)
     return -1;
 }
 
-
 int TableSet(struct Table *Tbl, const Str *Key, struct Value *Val)
 {
     int HashPos;
@@ -87,7 +81,7 @@ int TableSet(struct Table *Tbl, const Str *Key, struct Value *Val)
     if (HashPos == -1)
     {
         if (AddAt == -1)
-            Fail("table '%s' is full\n", Tbl->Name);
+            Fail("variable table is full\n");
         
         else
         {   /* add it to the table */
@@ -100,7 +94,6 @@ int TableSet(struct Table *Tbl, const Str *Key, struct Value *Val)
     return TRUE;
 }
 
-
 int TableGet(struct Table *Tbl, const Str *Key, struct Value **Val)
 {
     int HashPos;