Language.Syntactic.Sharing.Graph

Representation and manipulation of abstract syntax graphs

Representation

newtype NodeId

Node identifier

Constructors

NodeId

Fields

nodeInteger :: Integer

Instances

Enum NodeId

Eq NodeId

Integral NodeId

Num NodeId

Ord NodeId

Real NodeId

Show NodeId

Ix NodeId

~ (* -> Constraint) p (Sat dom) => NodeEqEnv dom (EqEnv dom p)

VarEqEnv (EqEnv dom p)

showNode :: NodeId -> String

data Node a where

Placeholder for a syntax tree

Constructors

Node :: NodeId -> Node (Full a)

Instances

ToTree Node

Render Node

Constrained Node

(AlphaEq dom dom dom env, NodeEqEnv dom env) => AlphaEq Node Node dom env

class NodeEqEnv dom a where

Environment for alpha-equivalence

Methods

prjNodeEqEnv :: a -> NodeEnv dom (Sat dom)

modNodeEqEnv :: (NodeEnv dom (Sat dom) -> NodeEnv dom (Sat dom)) -> a -> a

Instances

~ (* -> Constraint) p (Sat dom) => NodeEqEnv dom (EqEnv dom p)

type EqEnv dom p = ([(VarId, VarId)], NodeEnv dom p)

type NodeEnv dom p = (Array NodeId Hash, Array NodeId (ASTB dom p))

data ASG dom a

"Abstract Syntax Graph"

A representation of a syntax tree with explicit sharing. An ASG is valid if and only if inlineAll succeeds (and the numNodes field is correct).

Constructors

ASG

Fields

topExpression :: ASTF (NodeDomain dom) a

Top-level expression

graphNodes :: [(NodeId, ASTSAT (NodeDomain dom))]

Mapping from node id to sub-expression

numNodes :: NodeId

Total number of nodes

type NodeDomain dom = (Node :+: dom) :|| Sat dom

showASG :: ToTree dom => ASG dom a -> String

Show syntax graph using ASCII art

drawASG :: ToTree dom => ASG dom a -> IO ()

Print syntax graph using ASCII art

reindexNodesAST :: (NodeId -> NodeId) -> AST (NodeDomain dom) a -> AST (NodeDomain dom) a

Update the node identifiers in an AST using the supplied reindexing function

reindexNodes :: (NodeId -> NodeId) -> ASG dom a -> ASG dom a

Reindex the nodes according to the given index mapping. The number of nodes is unchanged, so if the index mapping is not 1:1, the resulting graph will contain duplicates.

reindexNodesFrom0 :: ASG dom a -> ASG dom a

Reindex the nodes to be in the range [0 .. l-1], where l is the number of nodes in the graph

nubNodes :: ASG dom a -> ASG dom a

Remove duplicate nodes from a graph. The function only looks at the NodeId of each node. The numNodes field is updated accordingly.

Folding

data SyntaxPF dom a where

Pattern functor representation of an AST with Nodes

Constructors

AppPF :: a -> a -> SyntaxPF dom a

NodePF :: NodeId -> a -> SyntaxPF dom a

DomPF :: dom b -> SyntaxPF dom a

Instances

Functor (SyntaxPF dom)

foldGraph :: forall dom a b. (SyntaxPF dom b -> b) -> ASG dom a -> (b, (Array NodeId b, [(NodeId, b)]))

Folding over a graph

The user provides a function to fold a single constructor (an "algebra"). The result contains the result of folding the whole graph as well as the result of each internal node, represented both as an array and an association list. Each node is processed exactly once.

Inlining

inlineAll :: forall dom a. ConstrainedBy dom Typeable => ASG dom a -> ASTF dom a

Convert an ASG to an AST by inlining all nodes

nodeChildren :: ASG dom a -> [(NodeId, [NodeId])]

Find the child nodes of each node in an expression. The child nodes of a node n are the first nodes along all paths from n.

occurrences :: ASG dom a -> Array NodeId Int

Count the number of occurrences of each node in an expression

inlineSingle :: forall dom a. ConstrainedBy dom Typeable => ASG dom a -> ASG dom a

Inline all nodes that are not shared

Sharing

hashNodes :: Equality dom => ASG dom a -> (Array NodeId Hash, [(NodeId, Hash)])

Compute a table (both array and list representation) of hash values for each node

partitionNodes :: forall dom a. (Equality dom, AlphaEq dom dom (NodeDomain dom) (EqEnv (NodeDomain dom) (Sat dom))) => ASG dom a -> [[NodeId]]

Partitions the nodes such that two nodes are in the same sub-list if and only if they are alpha-equivalent.

cse :: (Equality dom, AlphaEq dom dom (NodeDomain dom) (EqEnv (NodeDomain dom) (Sat dom))) => ASG dom a -> ASG dom a

Common sub-expression elimination based on alpha-equivalence