added the graph source files

graph.go

@@ -0,0 +1,127 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// graph.go
+package expr
+
+import (
+	"fmt"
+	"strings"
+)
+
+func BuildGraph(root *term) (g string) {
+	//var sb strings.Builder
+	g = fmt.Sprintf("tree: %v", root)
+
+	r := NewReticle(root)
+	fmt.Println(r)
+	return
+}
+
+type NodeRef struct {
+	node  *term
+	pos   int
+	label string
+}
+
+type Level []*NodeRef
+
+type Reticle struct {
+	levels      []Level
+	left, right int
+	charWidth   int
+	colsWidth   []int
+}
+
+func NewExprReticle(e Expr) *Reticle {
+	tree, _ := e.(*ast)
+	return NewReticle(tree.root)
+}
+
+func NewReticle(tree *term) *Reticle {
+	r := &Reticle{levels: make([]Level, 0)}
+	r.build(tree, 0, 0)
+	r.computeCharWidth()
+	return r
+}
+
+func (r *Reticle) computeCharWidth() {
+	numCol := r.right - r.left + 1
+	r.colsWidth = make([]int, numCol)
+	for _, level := range r.levels {
+		for _, ref := range level {
+			c := ref.pos - r.left
+			if v := ref.node.value(); v != nil {
+				ref.label = fmt.Sprintf("%v", v)
+			} else {
+				ref.label = ref.node.source()
+			}
+			r.colsWidth[c] = max(r.colsWidth[c], len(ref.label)+2) // +2 to make room for brakets
+		}
+	}
+	r.charWidth = 0
+	for _, w := range r.colsWidth {
+		r.charWidth += w
+	}
+}
+
+func (r *Reticle) build(node *term, depth, pos int) {
+	var level Level
+	if node == nil {
+		return
+	}
+	if len(r.levels) == depth {
+		level = make(Level, 0)
+		r.levels = append(r.levels, level)
+	} else {
+		level = r.levels[depth]
+	}
+	ref := &NodeRef{node: node, pos: pos}
+	level = append(level, ref)
+	if r.left > pos {
+		r.left = pos
+	}
+	if r.right < pos {
+		r.right = pos
+	}
+	if node.children != nil {
+		halfPos := len(node.children) / 2
+		childPos := pos - halfPos - 1
+		for _, child := range node.children {
+			childPos++
+			if childPos == pos && (len(node.children)&1) == 0 {
+				childPos++
+			}
+			r.build(child, depth+1, childPos)
+		}
+	}
+	r.levels[depth] = level
+}
+
+func (r *Reticle) nodeInLevel(level []*NodeRef, index int) (node *NodeRef) {
+	for _, ref := range level {
+		if ref.pos-r.left == index {
+			node = ref
+			break
+		}
+	}
+	return
+}
+
+func (r *Reticle) String() string {
+	var sb strings.Builder
+	for _, level := range r.levels {
+		for j, w := range r.colsWidth {
+			var label string
+			if ref := r.nodeInLevel(level, j); ref != nil {
+				s := "(" + ref.label + ")"
+				label = fmt.Sprintf("%[1]*s", -w, fmt.Sprintf("%[1]*s", (w+len(s))/2, s))
+			} else {
+				label = strings.Repeat(" ", w)
+			}
+			sb.WriteString(label)
+		}
+		sb.WriteByte('\n')
+	}
+	return sb.String()
+}

graph_test.go

@@ -0,0 +1,33 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// graph_test.go
+package expr
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestGraph(t *testing.T) {
+	// tk0 := NewToken(0, 0, SymChangeSign, "-")
+	tk1 := NewValueToken(0, 0, SymInteger, "100", 100)
+	tk2 := NewToken(0, 0, SymPlus, "+")
+	tk3 := NewValueToken(0, 0, SymInteger, "200", 200)
+
+	tree := NewAst()
+	// tree.addToken(tk0)
+	tree.addToken(tk1)
+	tree.addToken(tk2)
+	tree.addToken(tk3)
+	tk4 := NewToken(0, 0, SymPlus, "-")
+	tk5 := NewValueToken(0, 0, SymInteger, "50", 50)
+	tree.addToken(tk4)
+	tree.addToken(tk5)
+
+	g := BuildGraph(tree.root)
+	fmt.Println(g)
+}