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public abstract class PremonCon

(source file: PremonCon.java)
java.lang.Object
   |
   +----Printable
           |
           +----PremonCon
The pure class interface. 
public abstract class PremonCon
  extends Printable
The syntactic class of contexts .

Author:
Alan Jeffrey
Version: v1.0 1998/06/10

Constuctor Index

O PremonCon()

Variables Index

O empty
An empty context.

Methods

O binds(PremonVar)
Does this context bind a given variable?
O comp(PremonCon)
Compose this context with another.
O hide(PremonCon)
Remove the variables in one context from the current ones.
O lookup(String)
Look up a variable in the context.
O semantics()
The semantics of the context as an object.
O semanticsTo(PremonCon)
The semantics of this context as a shuffle.
O shuffleFromVar(PremonVar)
The (partial) shuffle from a variable to this context. The shuffle will be total if this
O shuffleTo(PremonCon)
The (partial) shuffle from this context to another. The shuffle will be total if Gamma is
O shuffleToVar(PremonVar)
The (partial) shuffle from this context to a variable. The shuffle will be total if this
O uniq()
`Uniqueify' the context, by removing any duplicate variables.

Constructors

O PremonCon
public PremonCon();

Variables

O empty
public static final PremonCon empty;
An empty context.

Methods

O hide
public abstract PremonCon hide(PremonCon Gamma);
Remove the variables in one context from the current ones.

Parameters:
Gamma - the variables to remove.
Returns:
this context with the variables from Gamma removed.

O binds

public abstract boolean binds(PremonVar x);
Does this context bind a given variable?

Parameters:
x - the variable to check.
Returns:
true if this context contains x.

O uniq

public abstract PremonCon uniq();
`Uniqueify' the context, by removing any duplicate variables.

Returns:
this context with any duplicate variables removed.

O semantics

public abstract Obj semantics();
The semantics of the context as an object.

Returns:
[[]]

O shuffleTo

public abstract Shuffle shuffleTo(PremonCon Gamma);
The (partial) shuffle from this context to another. The shuffle will be total if Gamma is contained in this context.

Parameters:
Gamma - the context to shuffle to.
Returns:
a shuffle [[this]] [[]]

O shuffleFromVar

public abstract Shuffle shuffleFromVar(PremonVar x);
The (partial) shuffle from a variable to this context. The shuffle will be total if this context binds at most x.

Parameters:
x - the variable to shuffle from.
Returns:
a shuffle [[x:T]] [[this]]

O shuffleToVar

public abstract Shuffle shuffleToVar(PremonVar x);
The (partial) shuffle from this context to a variable. The shuffle will be total if this context binds at least x.

Parameters:
the - variable to shuffle to.
Returns:
a shuffle [[this]] [[x:T]]

O lookup

public abstract PremonVar lookup(String s)
  throws TypeError;
Look up a variable in the context.

Parameters:
s - the name of the variable to find.
Returns:
the variable of that name in this context.
Throws:
TypeError -thrown if this context does not contain s.

O comp

public PremonCon comp(PremonCon Gamma);
Compose this context with another.

Parameters:
Gamma - the context to compose with.
Returns:
the composite of the two contexts.

O semanticsTo

public Mor semanticsTo(PremonCon Gamma);
The semantics of this context as a shuffle.

Parameters:
Gamma - the context to shuffle to.
Returns:
[[[this : Gamma]]

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