82 lines
2.9 KiB
C
82 lines
2.9 KiB
C
//Defining a symbol table
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//Using a Linked List Structure. Head of linked List points to parent scope (if one exists)
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//Tail of Linked List points to a List of child scopes
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#include "symbol_table.h"
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SymbolTable* CreateScope(SymbolTable* ParentScope, int Line, int Column){
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SymbolTable* table = (SymbolTable*)malloc(sizeof(SymbolTable));
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table->Line_Number = Line;
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table->Column_Number = Column;
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table->Parent_Scope = ParentScope;
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table->Children_Scope = NULL;
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table->entries = NULL;
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if(ParentScope != NULL){
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if(ParentScope->Children_Scope == NULL){
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ListOfTable* newEntry = (ListOfTable*)malloc(sizeof(ListOfTable));
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newEntry->next = NULL;
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//newEntry->prev = NULL;
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newEntry->table = table;
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ParentScope->Children_Scope = newEntry;
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} else{
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ListOfTable* newEntry = (ListOfTable*)malloc(sizeof(ListOfTable));
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//newEntry->prev = NULL;
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newEntry->table= table;
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ListOfTable* oldEntry = ParentScope->Children_Scope;
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ParentScope->Children_Scope = newEntry;
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newEntry->next = oldEntry;
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}
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}
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return table;
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}
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TableNode* CreateEntry(SymbolTable* table, char* typeOf, char* id){
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TableNode* newEntry = (TableNode*)malloc(sizeof(TableNode));
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newEntry->theType = typeOf;
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newEntry->theName = id;
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if(table->entries == NULL){
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table->entries = newEntry;
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return newEntry;
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} else{
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TableNode* oldEntry = table->entries;
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table->entries = newEntry;
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newEntry->next = oldEntry;
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return newEntry;
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}
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}
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TableNode * table_lookup(SymbolTable * table, char * x){
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TableNode * entrie = table->entries;
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for(; entrie != NULL; entrie = entrie->next){
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if (!strcmp(entrie->theName, x)){
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return entrie;
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}
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}
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return NULL;
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}
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TableNode * look_up(SymbolTable * table, char * x){
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if(table == NULL){
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return NULL;
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}
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TableNode * ret = table_lookup(table, x);
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if (ret != NULL){
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return ret;
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}
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return look_up(table->Parent_Scope, x);
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}
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//uncomment the below main function along with the headers above for a simple standalone test of table and entry creation
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int main(){
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char* String = "STRING";
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char* X = "X";
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SymbolTable* Second = CreateScope(NULL, 2,2);
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printf("Line number is %d, Column number of scope is %d\n",Second->Line_Number,Second->Column_Number);
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TableNode* First_Entry = CreateEntry(Second,String,X);
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printf("The type of the first entry is %s\n",First_Entry->theType);
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return 0;
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}
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