org.norecess.citkit.symboltable
Class HashSymbolTable<A>

java.lang.Object
  org.norecess.citkit.symboltable.HashSymbolTable<A>

All Implemented Interfaces:

SymbolTable<A>

public class HashSymbolTable<A>
extends java.lang.Object
implements SymbolTable<A>

Implements a symbol table for a compiler of Hobbes and perhaps other languages

To create a new, initial symbol table, use HashSymbolTable(). To create a chained symbol table (for nested scopes), use HashSymbolTable(SymbolTable).

Author:

Jeremy D. Frens

Constructor Summary

HashSymbolTable()
Builds a new, initial symbol table.

HashSymbolTable(SymbolTable<A> previous)
Builds a new symbol table using the specified symbol table as the previous symbol table for the previous scope.

Method Summary

void	add(java.lang.String name, A value) Adds a name with an associated value to the current symbol table..
void	add(Symbol variable, A value) Adds a new variable to the current symbol table.
boolean	equals(java.lang.Object other)
A	get(ISymbol variable) Returns the value associated with the specified variable.
A	get(java.lang.String name) Invokes get(ISymbol).
java.util.Set<Symbol>	getSymbols() Returns the symbols in the current scope.
java.lang.String	getVariablesAsString() Returns the variables of the scope.
int	hashCode()
A	set(java.lang.String name, A value) Sets a value associated with a name..
A	set(Symbol variable, A value) Changes the value associated with the specified variable.
A	setInCurrentScope(Symbol variable, A value) Changes the value associated with the specified variable only in the current scope.
java.lang.String	toString() The symbol table as a string.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

HashSymbolTable

public HashSymbolTable()

Builds a new, initial symbol table.

HashSymbolTable

public HashSymbolTable(SymbolTable<A> previous)

Builds a new symbol table using the specified symbol table as the previous symbol table for the previous scope.

Parameters:

previous - the previous symbol table.

Method Detail

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

add

public void add(Symbol variable,
                A value)

Description copied from interface: SymbolTable

Adds a new variable to the current symbol table. This does not check the previous symbol table (for previous variable scopes) to see if this shadows an earlier declaration; an exception is thrown when the variable is already declared in the current symbol table.

Specified by:

add in interface SymbolTable<A>

Parameters:

variable - the new variable to add to the symbol table.

value - the new value to associate with the new variable.

add

public void add(java.lang.String name,
                A value)

Description copied from interface: SymbolTable

Adds a name with an associated value to the current symbol table..

Specified by:

add in interface SymbolTable<A>

See Also:

SymbolTable.add(Symbol, Object)

get

public A get(ISymbol variable)

Returns the value associated with the specified variable. The variable is searched for in all of the previous scopes.

Specified by:

get in interface SymbolTable<A>

Parameters:

variable - the variable to search for.

Returns:

the value associated with the variable; null if the variable isn't found.

get

public A get(java.lang.String name)

Invokes get(ISymbol).

Specified by:

get in interface SymbolTable<A>

See Also:

SymbolTable.get(ISymbol)

getSymbols

public java.util.Set<Symbol> getSymbols()

Returns the symbols in the current scope.

Specified by:

getSymbols in interface SymbolTable<A>

set

public A set(Symbol variable,
             A value)

Changes the value associated with the specified variable. The variable is searched for in all of the previous scopes; the old value is returned.

Specified by:

set in interface SymbolTable<A>

Parameters:

variable - the variable to search for.

value - the new value for the variable.

Returns:

the old value associated with the variable.

set

public A set(java.lang.String name,
             A value)

Sets a value associated with a name..

Specified by:

set in interface SymbolTable<A>

See Also:

SymbolTable.set(Symbol, Object)

setInCurrentScope

public A setInCurrentScope(Symbol variable,
                           A value)

Changes the value associated with the specified variable only in the current scope. If it's not already defined, that's an error. The old value is returned.

Parameters:

variable - the variable to search for.

value - the new value for the variable.

Returns:

the old value associated with the variable.

Throws:

InvalidVariableException - when the variable is undeclared (in this or any previous scope).

toString

public java.lang.String toString()

The symbol table as a string.

Overrides:

toString in class java.lang.Object

getVariablesAsString

public java.lang.String getVariablesAsString()

Returns the variables of the scope. Useful in debugging.

Specified by:

getVariablesAsString in interface SymbolTable<A>