I am creating a symbol table class to be used with an analyzer/parser I’ve written for a compilers course. Everything has been going well so far, but I cannot get these class files to compile on my school’s Linux machines using g++:
SymbolTable.h:
// Multiple definition guard
#ifndef SYMBOLTABLE_H
#defineSYMBOLTABLE_H
// Includes
#include <iostream>
#include <string>
#include "stddef.h"
// Namespace
using namespace std;
// Class for storing all encountered symbols while parsing
class SymbolTable
{
public:
SymbolTable(); // Constructor
~SymbolTable(); // Destructor
void scopeUp(); // Increases current scope
void scopeDown(); // Decreases current scope
void addSymbol(string symbolTitle); // Adds a symbol to table
void addSymboll(string symbolTitle); // g++ doesn't think this exists
private:
int scope;
// Structure for storing symbols. Currently only contains title from
// identifier. Will expand upon / derive from this structure after
// initial testing. Symbols are stored in a simple stack, with the
// container class responsible for keeping track of the top Symbol.
struct Symbol
{
Symbol* previousSymbol;
string title;
};
// Structure for tracking current scope. All symbols will belong to a
// particular scope, and are stored in a simple stack to maintain
// declaration order. When the scope changes, currentScope will point to
// a new scope structure with its own list of symbols. Scopes themselves
// are also stored in a stack, where currentScope points to the top.
struct Scope
{
Scope* previousScope;
Symbol* currentSymbol;
};
Scope* currentScope;
// This is a recursive display function used for printing all of the items
// in a given scope. This is called from within the scopeDown function, so
// that the final list of items for that scope can be logged before it is
// destroyed
void displayScope(Symbol* displaySymbol);
};
#endif // Multiple definition guard
SymbolTable.cpp:
// Multiple definition guard
#ifndef SYMBOLTABLE_CPP
#define SYMBOLTABLE_CPP
// Includes
#include "SymbolTable.h"
// Constructor
SymbolTable::SymbolTable()
{
scope = 0;
currentScope = NULL;
return;
}
// Destructor
SymbolTable::~SymbolTable()
{
Scope* nextScopeToDelete = NULL;
Symbol* nextSymbolToDelete = NULL;
// While there are scopes left to delete from the table...
while(currentScope != NULL)
{
// Save the pointer to the next scope on the stack
nextScopeToDelete = currentScope->previousScope;
// While there are symbols left to delete from the scope...
while(currentScope->currentSymbol != NULL)
{
// Save the pointer to the next symbol on the stack
nextSymbolToDelete = currentScope->currentSymbol->previousSymbol;
// For debugging
cout << "deleting symbol " << currentScope->currentSymbol->title << endl;
// Delete the current top symbol
delete currentScope->currentSymbol;
// Move on to the next one
currentScope->currentSymbol = nextSymbolToDelete;
}
// For debugging
cout << "deleting scope " << scope << endl;
// Delete the current top scope
delete currentScope;
scope--;
// Move on to the next one
currentScope = nextScopeToDelete;
}
return;
}
// This is a recursive display function used for printing all of the items
// in a given scope. This is called from within the scopeDown function, so
// that the final list of items for that scope can be logged before it is
// destroyed
void SymbolTable::displayScope(Symbol* displaySymbol)
{
// If we've reached the bottom of the scope stack...
if(displaySymbol == NULL)
{
return; // Nothing to do
}
// We haven't reached the bottom of the scope stack
else
{
displaySymbol = displaySymbol->previousSymbol; // Keep going
displayScope(displaySymbol); // Recursive call
}
// Display this symbol after all lower ones have been displayed recursively
cout << displaySymbol->title << endl;
return;
}
// A new procedure has caused us to increase scope, so we'll create a new
// scope structure with its own symbol stack
void SymbolTable::scopeUp()
{
// Generate the new scope structure
Scope* newScope = new Scope;
newScope->previousScope = currentScope;
newScope->currentSymbol = NULL;
// Notification for debugging
cout << "ENTERING SCOPE " << scope + 1 << endl;
cout << "--------------------------------------------------";
cout << "-------------------------" << endl;
// Switch to the new scope
currentScope = newScope;
scope++;
return;
}
// The end of a procedure has caused us to decrement scope, so we'll delete
// the contents of the current one and fall back to the last scope on the stack
void SymbolTable::scopeDown()
{
// If we're already at the bottom of the stack...
if(currentScope == 0)
{
// Something is very wrong
cerr << "CANNOT DELETE SCOPE 0!!!!" << endl;
}
else
{
// Save the pointer to the next scope on the stack
Scope* previousScope = currentScope->previousScope;
Symbol* nextSymbolToDelete = NULL;
// Display the contents of this scope before deleting it (debugging)
displayScope(currentScope->currentSymbol);
// While there are still symbols in this scope to delete...
while(currentScope->currentSymbol != NULL)
{
// Save the pointer to the next symbol on the stack
nextSymbolToDelete = currentScope->currentSymbol->previousSymbol;
// Delete the current top symbol on the stack
delete currentScope->currentSymbol;
// Move on to the next one
currentScope->currentSymbol = nextSymbolToDelete;
}
// Notification for debugging
cout << "EXITING SCOPE " << scope-- << endl;
cout << "==================================================";
cout << "=========================" << endl;
// Delete the old top scope from the stack
delete currentScope;
// Move on to the next one
currentScope = previousScope;
}
return;
}
// Adds a symbol to the table. Specifically: adds a symbol to the top of the
// symbol stack in the scope at the top of the scope stack. This will soon be
// interfacing with more expansive data structure, but currently just stores
// the title of the symbol as detected in the parser.
void SymbolTable::addSymbol(string symbolTitle)
{
Symbol* newSymbol = new Symbol;
newSymbol->previousSymbol = currentScope->currentSymbol;
newSymbol->title = symbolTitle;
currentScope->currentSymbol = newSymbol;
return;
}
// g++ doesn't think this was declared in the class
void SymbolTable::addSymboll(string symbolTitle)
{
Symbol* newSymbol = new Symbol;
newSymbol->previousSymbol = currentScope->currentSymbol;
newSymbol->title = symbolTitle;
currentScope->currentSymbol = newSymbol;
return;
}
#endif // Multiple definition guard
Errors:
[...]$ touch SymbolTable.h SymbolTable.cpp
[...]$ g++ -c SymbolTable.cpp
SymbolTable.cpp:67: error: no âvoid SymbolTable::displayScope(SymbolTable::Symbol*)â member function declared in class âSymbolTableâ
SymbolTable.cpp:167: error: no âvoid SymbolTable::addSymboll(std::string)â member function declared in class âSymbolTableâ
[...]$
As far as I can tell, it seemed to think my displayScope function was not declared in the class header file. In order to investigate this further, I added a new function called addSymboll which was identical to the existing addSymbol function. However, it’s giving me the same error message for this new function. In fact, after a couple of hours spent trying to compile this, it seems that I cannot add any new functions to this class at all. I am at a complete loss as to what could be causing this. Any ideas would be appreciated!
I had previously only been deleting the object (.o) files when cleaning. What I ended up having to do here was delete the .gch files as well. There was nothing wrong with the actual code or g++ (despite the old version running on the school servers).