forked from LS6-Events/astra
/
expression.go
180 lines (152 loc) · 3.67 KB
/
expression.go
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package astTraversal
import (
"errors"
"go/ast"
"go/token"
"go/types"
"strings"
)
type ExpressionTraverser struct {
Traverser *BaseTraverser
Node ast.Expr
File *FileNode
ReturnNum int
}
func (t *BaseTraverser) Expression(node ast.Expr) *ExpressionTraverser {
return &ExpressionTraverser{
Traverser: t,
Node: node,
File: t.ActiveFile(),
ReturnNum: 0,
}
}
func (e *ExpressionTraverser) SetReturnNum(returnNum int) *ExpressionTraverser {
e.ReturnNum = returnNum
return e
}
func (e *ExpressionTraverser) BuiltInFunctions(callExpr *ast.CallExpr) (types.Type, error) {
if ident, ok := callExpr.Fun.(*ast.Ident); ok {
switch ident.Name {
case "new":
fallthrough
case "make":
arg := callExpr.Args[0]
return e.Traverser.Expression(arg).Type()
case "len":
return types.Typ[types.Int], nil
}
}
return nil, nil
}
func (e *ExpressionTraverser) Value() (string, error) {
switch n := e.Node.(type) {
case *ast.BasicLit:
value := n.Value
if n.Kind == token.STRING {
value = strings.Trim(value, "\"")
}
return value, nil
case *ast.Ident:
obj, err := e.File.Package.FindObjectForIdent(n)
if err != nil {
return "", err
}
if constant, ok := obj.(*types.Const); ok {
return constant.Val().String(), nil
}
node, err := e.File.Package.ASTAtPos(obj.Pos())
if err != nil {
return "", err
}
declaration, err := e.Traverser.Declaration(node, n.Name)
if err != nil {
return "", err
}
astNode, err := declaration.Value()
if err != nil {
return "", err
}
exprNode, ok := astNode.(ast.Expr)
if !ok {
return "", errors.New("astNode is not of type ast.Expr")
}
return e.Traverser.Expression(exprNode).Value()
case *ast.SelectorExpr:
obj, err := e.File.Package.FindObjectForIdent(n.Sel)
if err != nil {
return "", err
}
pkg := e.Traverser.Packages.FindOrAdd(obj.Pkg().Path())
_, err = e.Traverser.Packages.Get(pkg)
if err != nil {
return "", err
}
obj, err = pkg.FindObjectForIdentFuzzy(n.Sel)
if err != nil {
return "", err
}
if constant, ok := obj.(*types.Const); ok {
return constant.Val().String(), nil
}
node, err := pkg.ASTAtPos(obj.Pos())
if err != nil {
return "", err
}
declaration, err := e.Traverser.Declaration(node, n.Sel.Name)
if err != nil {
return "", err
}
astNode, err := declaration.Value()
if err != nil {
return "", err
}
exprNode, ok := astNode.(ast.Expr)
if !ok {
return "", errors.New("astNode is not of type ast.Expr")
}
return e.Traverser.Expression(exprNode).Value()
}
return "", errors.New("value not retrievable")
}
func (e *ExpressionTraverser) Type() (types.Type, error) {
switch n := e.Node.(type) {
case *ast.StarExpr:
return e.Traverser.Expression(n.X).Type()
case *ast.UnaryExpr:
return e.Traverser.Expression(n.X).Type()
case *ast.Ident:
obj, err := e.File.Package.FindObjectForIdentFuzzy(n)
if err != nil {
return nil, err
}
return obj.Type(), nil
case *ast.SelectorExpr:
obj, err := e.File.Package.FindObjectForIdent(n.Sel)
if err != nil {
return nil, err
}
return obj.Type(), nil
case *ast.ArrayType:
return e.File.Package.FindTypeForExpr(n)
case *ast.MapType:
return e.File.Package.FindTypeForExpr(n)
case *ast.CompositeLit:
return e.Traverser.Expression(n.Type).Type()
case *ast.BasicLit:
return e.File.Package.FindTypeForExpr(n)
case *ast.CallExpr:
result, err := e.BuiltInFunctions(n)
if err != nil {
return nil, err
}
if result != nil {
return result, err
}
callExpr, err := e.Traverser.CallExpression(n)
if err != nil {
return nil, err
}
return callExpr.ReturnType(e.ReturnNum)
}
return nil, errors.New("unsupported expression type")
}