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graph: imported graph as a subtree
This commit is contained in:
Brendan Tracey
408
graph/formats/dot/ast/ast.go
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408
graph/formats/dot/ast/ast.go
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@@ -0,0 +1,408 @@
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// This file is dual licensed under CC0 and The gonum license.
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//
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// Copyright ©2017 The gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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// Copyright ©2017 Robin Eklind.
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// This file is made available under a Creative Commons CC0 1.0
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// Universal Public Domain Dedication.
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// Package ast declares the types used to represent abstract syntax trees of
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// Graphviz DOT graphs.
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package ast
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import (
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"bytes"
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"fmt"
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)
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// === [ File ] ================================================================
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// A File represents a DOT file.
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//
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// Examples.
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//
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// digraph G {
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// A -> B
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// }
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// graph H {
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// C - D
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// }
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type File struct {
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// Graphs.
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Graphs []*Graph
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}
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// String returns the string representation of the file.
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func (f *File) String() string {
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buf := new(bytes.Buffer)
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for i, graph := range f.Graphs {
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if i != 0 {
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buf.WriteString("\n")
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}
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buf.WriteString(graph.String())
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}
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return buf.String()
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}
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// === [ Graphs ] ==============================================================
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// A Graph represents a directed or an undirected graph.
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//
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// Examples.
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//
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// digraph G {
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// A -> {B C}
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// B -> C
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// }
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type Graph struct {
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// Strict graph; multi-edges forbidden.
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Strict bool
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// Directed graph.
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Directed bool
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// Graph ID; or empty if anonymous.
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ID string
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// Graph statements.
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Stmts []Stmt
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}
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// String returns the string representation of the graph.
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func (g *Graph) String() string {
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buf := new(bytes.Buffer)
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if g.Strict {
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buf.WriteString("strict ")
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}
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if g.Directed {
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buf.WriteString("digraph ")
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} else {
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buf.WriteString("graph ")
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}
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if len(g.ID) > 0 {
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fmt.Fprintf(buf, "%s ", g.ID)
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}
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buf.WriteString("{\n")
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for _, stmt := range g.Stmts {
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fmt.Fprintf(buf, "\t%s\n", stmt)
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}
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buf.WriteString("}")
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return buf.String()
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}
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// === [ Statements ] ==========================================================
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// A Stmt represents a statement, and has one of the following underlying types.
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//
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// *NodeStmt
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// *EdgeStmt
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// *AttrStmt
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// *Attr
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// *Subgraph
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type Stmt interface {
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fmt.Stringer
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// isStmt ensures that only statements can be assigned to the Stmt interface.
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isStmt()
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}
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// --- [ Node statement ] ------------------------------------------------------
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// A NodeStmt represents a node statement.
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//
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// Examples.
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//
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// A [color=blue]
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type NodeStmt struct {
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// Node.
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Node *Node
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// Node attributes.
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Attrs []*Attr
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}
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// String returns the string representation of the node statement.
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func (e *NodeStmt) String() string {
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buf := new(bytes.Buffer)
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buf.WriteString(e.Node.String())
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if len(e.Attrs) > 0 {
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buf.WriteString(" [")
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for i, attr := range e.Attrs {
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if i != 0 {
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buf.WriteString(" ")
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}
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buf.WriteString(attr.String())
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}
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buf.WriteString("]")
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}
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return buf.String()
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}
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// --- [ Edge statement ] ------------------------------------------------------
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// An EdgeStmt represents an edge statement.
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//
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// Examples.
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//
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// A -> B
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// A -> {B C}
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// A -> B -> C
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type EdgeStmt struct {
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// Source vertex.
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From Vertex
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// Outgoing edge.
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To *Edge
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// Edge attributes.
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Attrs []*Attr
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}
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// String returns the string representation of the edge statement.
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func (e *EdgeStmt) String() string {
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buf := new(bytes.Buffer)
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fmt.Fprintf(buf, "%s %s", e.From, e.To)
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if len(e.Attrs) > 0 {
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buf.WriteString(" [")
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for i, attr := range e.Attrs {
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if i != 0 {
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buf.WriteString(" ")
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}
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buf.WriteString(attr.String())
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}
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buf.WriteString("]")
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}
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return buf.String()
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}
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// An Edge represents an edge between two vertices.
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type Edge struct {
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// Directed edge.
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Directed bool
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// Destination vertex.
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Vertex Vertex
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// Outgoing edge; or nil if none.
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To *Edge
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}
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// String returns the string representation of the edge.
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func (e *Edge) String() string {
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op := "--"
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if e.Directed {
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op = "->"
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}
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if e.To != nil {
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return fmt.Sprintf("%s %s %s", op, e.Vertex, e.To)
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}
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return fmt.Sprintf("%s %s", op, e.Vertex)
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}
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// --- [ Attribute statement ] -------------------------------------------------
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// An AttrStmt represents an attribute statement.
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//
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// Examples.
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//
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// graph [rankdir=LR]
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// node [color=blue fillcolor=red]
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// edge [minlen=1]
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type AttrStmt struct {
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// Graph component kind to which the attributes are assigned.
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Kind Kind
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// Attributes.
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Attrs []*Attr
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}
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// String returns the string representation of the attribute statement.
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func (a *AttrStmt) String() string {
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buf := new(bytes.Buffer)
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fmt.Fprintf(buf, "%s [", a.Kind)
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for i, attr := range a.Attrs {
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if i != 0 {
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buf.WriteString(" ")
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}
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buf.WriteString(attr.String())
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}
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buf.WriteString("]")
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return buf.String()
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}
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// Kind specifies the set of graph components to which attribute statements may
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// be assigned.
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type Kind uint
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// Graph component kinds.
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const (
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KindGraph Kind = iota // graph
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KindNode // node
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KindEdge // edge
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)
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// String returns the string representation of the graph component kind.
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func (k Kind) String() string {
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switch k {
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case KindGraph:
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return "graph"
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case KindNode:
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return "node"
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case KindEdge:
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return "edge"
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}
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panic(fmt.Sprintf("invalid graph component kind (%d)", uint(k)))
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}
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// --- [ Attribute ] -----------------------------------------------------------
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// An Attr represents an attribute.
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//
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// Examples.
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//
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// rank=same
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type Attr struct {
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// Attribute key.
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Key string
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// Attribute value.
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Val string
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}
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// String returns the string representation of the attribute.
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func (a *Attr) String() string {
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return fmt.Sprintf("%s=%s", a.Key, a.Val)
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}
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// --- [ Subgraph ] ------------------------------------------------------------
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// A Subgraph represents a subgraph vertex.
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//
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// Examples.
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//
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// subgraph S {A B C}
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type Subgraph struct {
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// Subgraph ID; or empty if none.
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ID string
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// Subgraph statements.
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Stmts []Stmt
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}
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// String returns the string representation of the subgraph.
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func (s *Subgraph) String() string {
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buf := new(bytes.Buffer)
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if len(s.ID) > 0 {
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fmt.Fprintf(buf, "subgraph %s ", s.ID)
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}
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buf.WriteString("{")
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for i, stmt := range s.Stmts {
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if i != 0 {
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buf.WriteString(" ")
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}
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buf.WriteString(stmt.String())
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}
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buf.WriteString("}")
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return buf.String()
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}
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// isStmt ensures that only statements can be assigned to the Stmt interface.
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func (*NodeStmt) isStmt() {}
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func (*EdgeStmt) isStmt() {}
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func (*AttrStmt) isStmt() {}
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func (*Attr) isStmt() {}
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func (*Subgraph) isStmt() {}
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// === [ Vertices ] ============================================================
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// A Vertex represents a vertex, and has one of the following underlying types.
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//
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// *Node
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// *Subgraph
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type Vertex interface {
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fmt.Stringer
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// isVertex ensures that only vertices can be assigned to the Vertex
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// interface.
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isVertex()
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}
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// --- [ Node identifier ] -----------------------------------------------------
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// A Node represents a node vertex.
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//
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// Examples.
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//
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// A
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// A:nw
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type Node struct {
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// Node ID.
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ID string
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// Node port; or nil if none.
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Port *Port
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}
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// String returns the string representation of the node.
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func (n *Node) String() string {
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if n.Port != nil {
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return fmt.Sprintf("%s%s", n.ID, n.Port)
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}
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return n.ID
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}
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// A Port specifies where on a node an edge should be aimed.
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type Port struct {
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// Port ID; or empty if none.
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ID string
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// Compass point.
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CompassPoint CompassPoint
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}
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// String returns the string representation of the port.
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func (p *Port) String() string {
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buf := new(bytes.Buffer)
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if len(p.ID) > 0 {
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fmt.Fprintf(buf, ":%s", p.ID)
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}
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if p.CompassPoint != CompassPointDefault {
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fmt.Fprintf(buf, ":%s", p.CompassPoint)
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}
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return buf.String()
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}
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// CompassPoint specifies the set of compass points.
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type CompassPoint uint
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// Compass points.
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const (
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CompassPointDefault CompassPoint = iota // _
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CompassPointNorth // n
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CompassPointNorthEast // ne
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CompassPointEast // e
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CompassPointSouthEast // se
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CompassPointSouth // s
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CompassPointSouthWest // sw
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CompassPointWest // w
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CompassPointNorthWest // nw
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CompassPointCenter // c
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)
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// String returns the string representation of the compass point.
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func (c CompassPoint) String() string {
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switch c {
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case CompassPointDefault:
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return "_"
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case CompassPointNorth:
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return "n"
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case CompassPointNorthEast:
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return "ne"
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case CompassPointEast:
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return "e"
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case CompassPointSouthEast:
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return "se"
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case CompassPointSouth:
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return "s"
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case CompassPointSouthWest:
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return "sw"
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case CompassPointWest:
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return "w"
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case CompassPointNorthWest:
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return "nw"
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case CompassPointCenter:
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return "c"
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}
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panic(fmt.Sprintf("invalid compass point (%d)", uint(c)))
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}
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// isVertex ensures that only vertices can be assigned to the Vertex interface.
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func (*Node) isVertex() {}
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func (*Subgraph) isVertex() {}
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