The LaSt context framework

Author(s): Per Cederberg.

Context sensitivity can be interesting for several different purposes, having different requirements on the context predicates. This module is an attempt at creating a uniform and general purpose interface for the context predicates needed.

The framework in this module is based on generic operators, calling the appropriate implementing predicate. All to avoid a massive amount of different predicates in the interface. Currently the framework within this module supports WSDL and HTML contexts, but it can be easily exendible for other types of terms.

• Usage and interface (context)
• Documentation on exports (context)

Usage and interface (context)

Documentation on exports (context)

REGTYPE: context/1:

Usage: context(T)

• Description: T is a context.
• Properties which are true globally: Defines a regular type. (regtype/1)

PREDICATE: html2context/3:

Usage 1: html2context(HTMLNode,HTMLTree,Context)

• Description: Creates a Context term for a HTMLNode that is a descendant from a top HTMLTree node.
• Should hold at call time: HTMLNode is any term. (term/1) HTMLTree is any term. (term/1) Context is a free variable. (var/1)
• Should hold upon exit: Context is a context. (context/1)

Usage 2: html2context(HTMLNode,HTMLTree,Context)

• Description: Accesses the HTMLNode and HTMLTree nodes from a Context term.
• Should hold at call time: HTMLNode is a free variable. (var/1) HTMLTree is a free variable. (var/1) Context is a context. (context/1)
• Should hold upon exit: HTMLNode is any term. (term/1) HTMLTree is any term. (term/1)

PREDICATE: wsdl2context/3:

Usage 1: wsdl2context(WSDLNode,WSDLTree,Context)

• Description: Creates a Context term for a WSDLNode that is a descendant from a top WSDLTree node.
• Should hold at call time: WSDLNode is any term. (term/1) WSDLTree is any term. (term/1) Context is a free variable. (var/1)
• Should hold upon exit: Context is a context. (context/1)

Usage 2: wsdl2context(WSDLNode,WSDLTree,Context)

• Description: Accesses the WSDLNode and WSDLTree nodes from a Context term.
• Should hold at call time: WSDLNode is a free variable. (var/1) WSDLTree is a free variable. (var/1) Context is a context. (context/1)
• Should hold upon exit: WSDLNode is any term. (term/1) WSDLTree is any term. (term/1)

PREDICATE: context_type/2:

Usage: context_type(Context,NodeType)

• Description: Accesses the NodeType for the Context.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: NodeType is currently instantiated to an atom. (atom/1)

PREDICATE: context_attribute/3:

Usage: context_attribute(Context,Name,Value)

• Description: Accesses an attribute Names Value in the Context. The predicate fails if there is no attribute named Name.
• Should hold at call time: Context is a context. (context/1) Name is currently instantiated to an atom. (atom/1)
• Should hold upon exit: Value is currently instantiated to an atom. (atom/1)

PREDICATE: context_data/2:

Usage: context_data(Context,DataLs)

• Description: Accesses the data for all the children to the Context. The data will be returned in a list (DataLs), but the list element type depends on the type of context. No nodes will be present in the list.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: DataLs is a list. (list/1)

PREDICATE: context_depth/2:

Usage: context_depth(Context,Depth)

• Description: Calculates the tree Depth of the Context.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: Depth is an integer. (int/1)

PREDICATE: context_position/2:

Usage: context_position(Context,ChildNumber)

• Description: Calculates the ChildNumber, i.e. the position of the Context in the parent child list. The predicate fails if the Context hasn't got a parent.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: ChildNumber is an integer. (int/1)

PREDICATE: context_type_position/2:

Usage: context_type_position(Context,ChildNumber)

• Description: Calculates the ChildNumber, i.e. the position of the Context in the parent child list, only considering the siblings of the same type. The predicate fails if the Context hasn't got a parent.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: ChildNumber is an integer. (int/1)

PREDICATE: context_children/2:

Usage: context_children(Context,NumberOfChildren)

• Description: Calculates the NumberOfChildren to a Context node.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: NumberOfChildren is an integer. (int/1)

PREDICATE: context_parent/2:

Usage: context_parent(Context,ParentContext)

• Description: Finds the ParentContext to a Context.
• Should hold at call time: Parent is a context. (context/1)
• Should hold upon exit: ParentContext is a context. (context/1)

PREDICATE: context_ancestor/2:

Usage: context_ancestor(Context,AncestorContext)

• Description: Finds an AncestorContext to a Context. Upon backtracking the predicate returns all ancestors.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: AncestorContext is a context. (context/1)

PREDICATE: context_child/2:

Usage: context_child(Context,ChildContext)

• Description: Finds a ChildContext node to a Context node. The predicate will return all children upon backtracking.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: ChildContext is a context. (context/1)

PREDICATE: context_descendant/2:

Usage: context_descendant(Context,DescendantContext)

• Description: Finds a DescendantContext node to a Context node. Upon backtracking the predicate returns all descendants.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: DescendantContext is a context. (context/1)

PREDICATE: context_sibling/2:

Usage: context_sibling(Context,SiblingContext)

• Description: Finds a SiblingContext node to a Context node. The predicate will return all siblings upon backtracking. Note that the Context node is not considered a sibling to itself.
• Should hold at call time: Context is a context. (context/1)
• Should hold upon exit: SiblingContext is a context. (context/1)

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