util
Class SymbolTable

java.lang.Object
  util.SymbolTable

public class SymbolTable
extends java.lang.Object

Class for representing a class symbol table

Constructor Summary

SymbolTable()
SymbolTable constructor create an empty symbol table

Method Summary

void	add(java.lang.String s, java.lang.Object value) Adds a symbol to the symbol table if one does not already exist Sets the value of the symbol to the specified parameter
SymbolTable	clone() clone this symbol table as well as all parent symbol tables Note: does a shallow clone, does not copy keys or values Note also: this is an expensive operation
void	dump() For debugging -- dumps out entire symbol table Starts from highest scope level (Object class) and works towards the lowest scope level (current level)
void	enterScope() Enter a new scope
void	exitScope() Exit a scope
int	getCurrScopeLevel() Gets the current scope level of the symbol table (first scope starts at 1)
int	getCurrScopeSize() Gets the number of entries in the current scope of the symbol table
int	getScopeLevel(java.lang.String s) Gets scope level of a symbol in the table (<0 means symbol not in table)
int	getSize() Gets the number of entries in all scopes of the symbol table Note: includes inherited scopes
java.lang.Object	lookup(java.lang.String s) Looks up a symbol in any scope in the symbol table
java.lang.Object	lookup(java.lang.String s, int level) Looks up a symbol in a particular scope in the symbol table as well as any outer scopes from that specified scope Note: an exception is thrown if the specified level is <0 or >= largest scope level
java.lang.Object	peek(java.lang.String s) Looks up a symbol in the current scope in the table
java.lang.Object	peek(java.lang.String s, int level) Looks up a symbol in a particular scope in the symbol table Note: an exception is thrown if the specified level is <0 or >= largest scope level
void	set(java.lang.String s, java.lang.Object val) Sets the value of an existing symbol in the innermost scope of the symbol table
void	set(java.lang.String s, java.lang.Object val, int level) Sets the value of an existing symbol in a particular scope of the symbol table (or an outer scope containing the specified scope)
void	setParent(SymbolTable parent) Set the parent symbol table

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SymbolTable

public SymbolTable()

SymbolTable constructor create an empty symbol table

Method Detail

setParent

public void setParent(SymbolTable parent)

Set the parent symbol table

Parameters:

parent - symbol table of the parent class

enterScope

public void enterScope()

Enter a new scope

exitScope

public void exitScope()

Exit a scope

add

public void add(java.lang.String s,
                java.lang.Object value)

Adds a symbol to the symbol table if one does not already exist Sets the value of the symbol to the specified parameter

Parameters:

s - symbol name (i.e., name of variable or method)

value - value of symbol (i.e., type)

lookup

public java.lang.Object lookup(java.lang.String s)

Looks up a symbol in any scope in the symbol table

Parameters:

s - string of symbol to lookup

Returns:

value of symbol (i.e., type), null if not found

lookup

public java.lang.Object lookup(java.lang.String s,
                               int level)

Looks up a symbol in a particular scope in the symbol table as well as any outer scopes from that specified scope Note: an exception is thrown if the specified level is <0 or >= largest scope level

Parameters:

s - string of symbol to lookup

level - scope level to lookup string (outermost scope is at level 0)

Returns:

value of symbol (i.e., type), null if not found in particular scope level

peek

public java.lang.Object peek(java.lang.String s)

Looks up a symbol in the current scope in the table

Parameters:

s - string of symbol to lookup

Returns:

value of symbol (i.e., type), null if not found

peek

public java.lang.Object peek(java.lang.String s,
                             int level)

Looks up a symbol in a particular scope in the symbol table Note: an exception is thrown if the specified level is <0 or >= largest scope level

Parameters:

s - string of symbol to lookup

level - scope level to lookup string (outermost scope is at level 0)

Returns:

value of symbol (i.e., type), null if not found in particular scope level

set

public void set(java.lang.String s,
                java.lang.Object val)

Sets the value of an existing symbol in the innermost scope of the symbol table

Parameters:

s - string of symbol to set

val - value to set the symbol to

set

public void set(java.lang.String s,
                java.lang.Object val,
                int level)

Sets the value of an existing symbol in a particular scope of the symbol table (or an outer scope containing the specified scope)

Parameters:

s - string of symbol to set

val - value to set the symbol to

level - scope level containing symbol to be set

getScopeLevel

public int getScopeLevel(java.lang.String s)

Gets scope level of a symbol in the table (<0 means symbol not in table)

Parameters:

s - string of symbol to lookup

Returns:

scope level

getSize

public int getSize()

Gets the number of entries in all scopes of the symbol table Note: includes inherited scopes

Returns:

size of current scope

getCurrScopeSize

public int getCurrScopeSize()

Gets the number of entries in the current scope of the symbol table

Returns:

size of current scope

getCurrScopeLevel

public int getCurrScopeLevel()

Gets the current scope level of the symbol table (first scope starts at 1)

Returns:

current scope level

clone

public SymbolTable clone()

clone this symbol table as well as all parent symbol tables Note: does a shallow clone, does not copy keys or values Note also: this is an expensive operation

Overrides:

clone in class java.lang.Object

Returns:

cloned symbol table

dump

public void dump()

For debugging -- dumps out entire symbol table Starts from highest scope level (Object class) and works towards the lowest scope level (current level)