145 lines
2.8 KiB
Go
145 lines
2.8 KiB
Go
// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
|
|
// All rights reserved.
|
|
|
|
// ast.go
|
|
package expr
|
|
|
|
import (
|
|
"errors"
|
|
"strings"
|
|
|
|
"git.portale-stac.it/go-pkg/expr/kern"
|
|
)
|
|
|
|
//-------- ast
|
|
|
|
type ast struct {
|
|
forest []*term
|
|
root *term
|
|
}
|
|
|
|
func NewAst() *ast {
|
|
return &ast{}
|
|
}
|
|
|
|
func (ast *ast) TypeName() string {
|
|
return "Expression"
|
|
}
|
|
|
|
func (ast *ast) ToForest() {
|
|
if ast.root != nil {
|
|
if ast.forest == nil {
|
|
ast.forest = make([]*term, 0)
|
|
}
|
|
ast.forest = append(ast.forest, ast.root)
|
|
ast.root = nil
|
|
}
|
|
}
|
|
|
|
func (ast *ast) String() string {
|
|
var sb strings.Builder
|
|
if ast.root == nil {
|
|
sb.WriteString("(nil)")
|
|
} else {
|
|
ast.root.toString(&sb)
|
|
}
|
|
return sb.String()
|
|
}
|
|
|
|
func (ast *ast) addTokens(tokens ...*Token) (err error) {
|
|
for _, tk := range tokens {
|
|
if _, err = ast.addToken(tk); err != nil {
|
|
break
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// func (expr *ast) addToken(tk *Token) (err error) {
|
|
// _, err = expr.addToken2(tk)
|
|
// return
|
|
// }
|
|
|
|
func (ast *ast) addToken(tk *Token) (t *term, err error) {
|
|
if t = newTerm(tk); t != nil {
|
|
err = ast.addTerm(t)
|
|
} else {
|
|
err = tk.Errorf("unexpected token %q", tk.String())
|
|
}
|
|
return
|
|
}
|
|
|
|
func (ast *ast) addTerm(node *term) (err error) {
|
|
if ast.root == nil {
|
|
ast.root = node
|
|
} else {
|
|
ast.root, err = ast.insert(ast.root, node)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (ast *ast) insert(tree, node *term) (root *term, err error) {
|
|
if tree.getPriority() < node.getPriority() {
|
|
root = tree
|
|
if tree.isComplete() {
|
|
var subRoot *term
|
|
last := tree.removeLastChild()
|
|
if subRoot, err = ast.insert(last, node); err == nil {
|
|
subRoot.setParent(tree)
|
|
}
|
|
} else {
|
|
node.setParent(tree)
|
|
}
|
|
} else if !node.isLeaf() {
|
|
root = node
|
|
tree.setParent(node)
|
|
} else {
|
|
err = node.Errorf("two adjacent operators: %q and %q", tree, node)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (ast *ast) Finish() {
|
|
if ast.root == nil && ast.forest != nil && len(ast.forest) >= 1 {
|
|
ast.root = ast.forest[len(ast.forest)-1]
|
|
ast.forest = ast.forest[0 : len(ast.forest)-1]
|
|
}
|
|
}
|
|
|
|
func (ast *ast) Eval(ctx kern.ExprContext) (result any, err error) {
|
|
defer func() {
|
|
if r := recover(); r != nil {
|
|
if errVal, ok := r.(error); ok {
|
|
err = errVal
|
|
}
|
|
}
|
|
if err == nil {
|
|
err = errors.New("unexpected error while evaluating the expression")
|
|
}
|
|
}()
|
|
|
|
ast.Finish()
|
|
|
|
if ast.root != nil {
|
|
// initDefaultVars(ctx)
|
|
if ast.forest != nil {
|
|
for _, root := range ast.forest {
|
|
if result, err = root.Compute(ctx); err == nil {
|
|
ctx.UnsafeSetVar(kern.ControlLastResult, result)
|
|
} else {
|
|
//err = fmt.Errorf("error in expression nr %d: %v", i+1, err)
|
|
break
|
|
}
|
|
}
|
|
}
|
|
if err == nil {
|
|
if result, err = ast.root.Compute(ctx); err == nil {
|
|
ctx.UnsafeSetVar(kern.ControlLastResult, result)
|
|
}
|
|
}
|
|
// } else {
|
|
// err = errors.New("empty expression")
|
|
}
|
|
return
|
|
}
|