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108 lines
5.7 KiB
Plaintext
108 lines
5.7 KiB
Plaintext
-- Pseudocode for collapsing a syntax graph.
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-- New stateful algorithm
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-- Note: Node refers to the FGL node, which is just an integer. The node label has to be looked up separately in the graph.
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-- The node label has all of the information about the node such as what SyntaxNode it represents.
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collapseRoots treeRoots = foldl' (collapseTree treeRoots)
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collapseNodes :: SyntaxGrrah -> SyntaxGraph
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collapseNodes originalGraph = finalGraph where
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-- findTreeRoots returns a list of nodes that will embed other nodes, but are not embedded themselves.
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-- These nodes are thus each a root of a collapsed node tree.
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treeRoots = findTreeRoots originalGraph
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-- Now collapse each tree of nodes
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finalGraph = collapseRoots treeRoots originalGraph treeRoots
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-- |findTreeRoots returns a list of nodes that might embed other nodes, but are not embedded themselves.
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-- These nodes are thus each a root of a collapsed node tree.
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-- A node is a treeRoot if all of these conditions are true:
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-- 1. The SyntaxNode can embed other nodes (i.e. nodeCanEmbed is true)
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-- 2. The node has at least one parent that can not embed (i.e. the node has a parent where nodeCanEmbed is false.)
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-- Note: A treeRoot may not actually have any embeddable children, since collapseTree will do nothing in that case.
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findTreeRoots :: SyntaxGraph -> [Node]
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-- filterNodes is a library function that returns a list of the nodes in the graph
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-- where the filter function is true.
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-- filterNodes :: (Node -> Bool) -> Graph -> [Node]
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findTreeRoots graph = filterNodes (isTreeRoot graph) graph
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isTreeRoot :: SyntaxGraph -> Node -> Bool
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isTreeRoot graph node = graphNodeCanEmbed graph node && hasAParentThatCannotEmbed where
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hasAParentThatCannotEmbed = not $ null parentsThatCannotEmbed
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parentsThatCannotEmbed = filter (graphNodeCanEmbed graph) (findParents graph node)
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findParents :: Graph -> Node -> [Node]
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findParents = _ -- TODO
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graphNodeCanEmbed :: Graph -> Node -> Bool
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graphNodeCanEmbed graph node = syntaxNodeCanEmbed $ lookupSyntaxNode graph node
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lookupSyntaxNode :: SyntaxGraph -> Node -> SyntaxNode
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collapseTree :: [Node] -> SyntaxGraph -> Node -> SyntaxGraph
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collapseTree treeRoots oldGraph rootNode = case childrenToEmbed of
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[] -> oldGraph
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_ -> finalGraph
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where
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-- TODO Write pseudocode for subfunctions
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childrenToEmbed = findChildrenToEmbed treeRoots rootNode oldGraph
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-- Recursively collapse the children nodes
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graphWithCollapsedChildren = collapseRoots treeRoots oldGraph childrenToEmbed
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-- Transfer the edges of the children to rootNode
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childEdgesToTransfer = findChildEdgesToTransfer childrenToEmbed graphWithCollapsedChildren
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graphWithChildEdgesDeleted = deleteChildEdges childEdgesToTransfer graphWithCollapsedChildren
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graphWithEdgesTransferred = addChildEdges rootNode childEdgesToTransfer graphWithChildEdgesDeleted
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-- Modify the rootNode label (i.e. SyntaxNode) to incorporate the children it is embedding
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graphWithChildrenCollapsed = embedChildSyntaxNodes rootNode childrenToEmbed graphWithEdgesTransferred
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-- Delete the children that have been embedded
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finalGraph = deleteChildren childrenToEmbed graphWithChildrenCollapsed
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-- | findChildrenToEmbed returns a list of the node's children that can be embedded
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-- A child can be embedded iff all of these conditions are true:
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-- 1. The node is not a treeRoot (otherwise a cycle of embedding could occur)
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-- 2. The SyntaxNode is embeddable (i.e. nodeIsEmbeddable is True)
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-- 3. The node has exactly one parent that can embed (i.e. nodeCanEmbed is True for one parent)
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findChildrenToEmbed :: Node -> SyntaxGraph -> [Node]
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findChildrenToEmbed treeRoots node graph = if graphNodeCanEmbed node graph
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then childrenToEmbed
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else []
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where
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childrenToEmbed = _ -- TODO
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-- | graphNodeCanEmbed returns true if the label (SyntaxNode) associated with the
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-- node can be embedded in other SyntaxNodes (i.e. nodeCanEmbed is True)
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graphNodeCanEmbed :: Node -> SyntaxGraph -> Bool
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graphNodeCanEmbed node graph = _
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-- OLD ALGORITHM
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-- To make the problem simpler, collapseNodes just cares about the
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collapseNodes :: SyntaxGraph -> SyntaxGraph
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collapseNodes inGraph = graphFold foldFunc initialOutputGraph inGraph where
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initialOutputGraph = emptyGraph
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foldFunc :: SyntaxGraph -> Context -> SyntaxGraph
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foldFunc oldGraph context = let node = nodeInContext context in
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-- The node can not be embedded, and can not embed other nodes, so it is by itself.
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-- We thus just add it to the accumulator graph.
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-- willEmbed is true iff the current node will embed other nodes in the graph
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| not (willBeEmbedded context inGraph) && not (willEmbed context inGraph) = context & oldGraph
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-- willBeEmbedded checks to see if the parent of the current node will embed the current node
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-- In this case the current node will be embedded, and does not embed other node.
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-- We do not add the current node since it will be embedded in its parent.
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-- This case is not necessary. If the current node were to be added, it would simply be
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-- removed again from the accumulation graph.
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| willBeEmbedded context inGraph && not (willEmbed context) = oldGraph
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-- This node will embed other nodes.
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-- First we find our children that will be embedded. If the child is in the
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-- oldGraph, then we also need to remove the child from the oldGraph.
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-- If the child is not yet in the oldGraph, then we just embed it.
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| willEmbed context inGraph =
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newGraph where
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(oldGraphChildren, oldGraphWithChildrenRemoved) = findAndRemoveChildren oldGraph context
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remainingChildrem = getRemainingChildren oldGraphChildren inGraph context
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embeddedNode = makeEmbeddedNode context oldGraphChildren remainingChildren
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newGarph = embeddedNode & oldGraphWithChildrenRemoved
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