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mirror of https://github.com/beego/bee.git synced 2024-12-23 11:40:48 +00:00
bee/vendor/github.com/derekparker/delve/proc/eval.go
2017-03-26 16:55:28 +02:00

1122 lines
29 KiB
Go

package proc
import (
"bytes"
"encoding/binary"
"fmt"
"go/ast"
"go/constant"
"go/parser"
"go/printer"
"go/token"
"reflect"
"github.com/derekparker/delve/dwarf/reader"
"golang.org/x/debug/dwarf"
)
// EvalExpression returns the value of the given expression.
func (scope *EvalScope) EvalExpression(expr string, cfg LoadConfig) (*Variable, error) {
t, err := parser.ParseExpr(expr)
if err != nil {
return nil, err
}
ev, err := scope.evalAST(t)
if err != nil {
return nil, err
}
ev.loadValue(cfg)
if ev.Name == "" {
ev.Name = expr
}
return ev, nil
}
func (scope *EvalScope) evalAST(t ast.Expr) (*Variable, error) {
switch node := t.(type) {
case *ast.CallExpr:
if len(node.Args) == 1 {
v, err := scope.evalTypeCast(node)
if err == nil {
return v, nil
}
_, isident := node.Fun.(*ast.Ident)
// we don't support function calls at the moment except for a few
// builtin functions so just return the type error here if the function
// isn't an identifier.
// More sophisticated logic will be required when function calls
// are implemented.
if err != reader.TypeNotFoundErr || !isident {
return v, err
}
}
return scope.evalBuiltinCall(node)
case *ast.Ident:
return scope.evalIdent(node)
case *ast.ParenExpr:
// otherwise just eval recursively
return scope.evalAST(node.X)
case *ast.SelectorExpr: // <expression>.<identifier>
// try to interpret the selector as a package variable
if maybePkg, ok := node.X.(*ast.Ident); ok {
if maybePkg.Name == "runtime" && node.Sel.Name == "curg" {
return scope.Thread.getGVariable()
} else if v, err := scope.packageVarAddr(maybePkg.Name + "." + node.Sel.Name); err == nil {
return v, nil
}
}
// if it's not a package variable then it must be a struct member access
return scope.evalStructSelector(node)
case *ast.TypeAssertExpr: // <expression>.(<type>)
return scope.evalTypeAssert(node)
case *ast.IndexExpr:
return scope.evalIndex(node)
case *ast.SliceExpr:
if node.Slice3 {
return nil, fmt.Errorf("3-index slice expressions not supported")
}
return scope.evalReslice(node)
case *ast.StarExpr:
// pointer dereferencing *<expression>
return scope.evalPointerDeref(node)
case *ast.UnaryExpr:
// The unary operators we support are +, - and & (note that unary * is parsed as ast.StarExpr)
switch node.Op {
case token.AND:
return scope.evalAddrOf(node)
default:
return scope.evalUnary(node)
}
case *ast.BinaryExpr:
return scope.evalBinary(node)
case *ast.BasicLit:
return newConstant(constant.MakeFromLiteral(node.Value, node.Kind, 0), scope.Thread), nil
default:
return nil, fmt.Errorf("expression %T not implemented", t)
}
}
func exprToString(t ast.Expr) string {
var buf bytes.Buffer
printer.Fprint(&buf, token.NewFileSet(), t)
return buf.String()
}
// Eval type cast expressions
func (scope *EvalScope) evalTypeCast(node *ast.CallExpr) (*Variable, error) {
argv, err := scope.evalAST(node.Args[0])
if err != nil {
return nil, err
}
argv.loadValue(loadSingleValue)
if argv.Unreadable != nil {
return nil, argv.Unreadable
}
fnnode := node.Fun
// remove all enclosing parenthesis from the type name
for {
p, ok := fnnode.(*ast.ParenExpr)
if !ok {
break
}
fnnode = p.X
}
styp, err := scope.Thread.dbp.findTypeExpr(fnnode)
if err != nil {
return nil, err
}
typ := resolveTypedef(styp)
converr := fmt.Errorf("can not convert %q to %s", exprToString(node.Args[0]), typ.String())
v := newVariable("", 0, styp, scope.Thread.dbp, scope.Thread)
v.loaded = true
switch ttyp := typ.(type) {
case *dwarf.PtrType:
switch argv.Kind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
// ok
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
// ok
default:
return nil, converr
}
n, _ := constant.Int64Val(argv.Value)
v.Children = []Variable{*(scope.newVariable("", uintptr(n), ttyp.Type))}
return v, nil
case *dwarf.UintType:
switch argv.Kind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
n, _ := constant.Int64Val(argv.Value)
v.Value = constant.MakeUint64(convertInt(uint64(n), false, ttyp.Size()))
return v, nil
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
n, _ := constant.Uint64Val(argv.Value)
v.Value = constant.MakeUint64(convertInt(n, false, ttyp.Size()))
return v, nil
case reflect.Float32, reflect.Float64:
x, _ := constant.Float64Val(argv.Value)
v.Value = constant.MakeUint64(uint64(x))
return v, nil
}
case *dwarf.IntType:
switch argv.Kind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
n, _ := constant.Int64Val(argv.Value)
v.Value = constant.MakeInt64(int64(convertInt(uint64(n), true, ttyp.Size())))
return v, nil
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
n, _ := constant.Uint64Val(argv.Value)
v.Value = constant.MakeInt64(int64(convertInt(n, true, ttyp.Size())))
return v, nil
case reflect.Float32, reflect.Float64:
x, _ := constant.Float64Val(argv.Value)
v.Value = constant.MakeInt64(int64(x))
return v, nil
}
case *dwarf.FloatType:
switch argv.Kind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
fallthrough
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
fallthrough
case reflect.Float32, reflect.Float64:
v.Value = argv.Value
return v, nil
}
case *dwarf.ComplexType:
switch argv.Kind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
fallthrough
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
fallthrough
case reflect.Float32, reflect.Float64:
v.Value = argv.Value
return v, nil
}
}
return nil, converr
}
func convertInt(n uint64, signed bool, size int64) uint64 {
buf := make([]byte, 64/8)
binary.BigEndian.PutUint64(buf, n)
m := 64/8 - int(size)
s := byte(0)
if signed && (buf[m]&0x80 > 0) {
s = 0xff
}
for i := 0; i < m; i++ {
buf[i] = s
}
return uint64(binary.BigEndian.Uint64(buf))
}
func (scope *EvalScope) evalBuiltinCall(node *ast.CallExpr) (*Variable, error) {
fnnode, ok := node.Fun.(*ast.Ident)
if !ok {
return nil, fmt.Errorf("function calls are not supported")
}
args := make([]*Variable, len(node.Args))
for i := range node.Args {
v, err := scope.evalAST(node.Args[i])
if err != nil {
return nil, err
}
args[i] = v
}
switch fnnode.Name {
case "cap":
return capBuiltin(args, node.Args)
case "len":
return lenBuiltin(args, node.Args)
case "complex":
return complexBuiltin(args, node.Args)
case "imag":
return imagBuiltin(args, node.Args)
case "real":
return realBuiltin(args, node.Args)
}
return nil, fmt.Errorf("function calls are not supported")
}
func capBuiltin(args []*Variable, nodeargs []ast.Expr) (*Variable, error) {
if len(args) != 1 {
return nil, fmt.Errorf("wrong number of arguments to cap: %d", len(args))
}
arg := args[0]
invalidArgErr := fmt.Errorf("invalid argument %s (type %s) for cap", exprToString(nodeargs[0]), arg.TypeString())
switch arg.Kind {
case reflect.Ptr:
arg = arg.maybeDereference()
if arg.Kind != reflect.Array {
return nil, invalidArgErr
}
fallthrough
case reflect.Array:
return newConstant(constant.MakeInt64(arg.Len), arg.mem), nil
case reflect.Slice:
return newConstant(constant.MakeInt64(arg.Cap), arg.mem), nil
case reflect.Chan:
arg.loadValue(loadFullValue)
if arg.Unreadable != nil {
return nil, arg.Unreadable
}
if arg.Base == 0 {
return newConstant(constant.MakeInt64(0), arg.mem), nil
}
return newConstant(arg.Children[1].Value, arg.mem), nil
default:
return nil, invalidArgErr
}
}
func lenBuiltin(args []*Variable, nodeargs []ast.Expr) (*Variable, error) {
if len(args) != 1 {
return nil, fmt.Errorf("wrong number of arguments to len: %d", len(args))
}
arg := args[0]
invalidArgErr := fmt.Errorf("invalid argument %s (type %s) for len", exprToString(nodeargs[0]), arg.TypeString())
switch arg.Kind {
case reflect.Ptr:
arg = arg.maybeDereference()
if arg.Kind != reflect.Array {
return nil, invalidArgErr
}
fallthrough
case reflect.Array, reflect.Slice, reflect.String:
if arg.Unreadable != nil {
return nil, arg.Unreadable
}
return newConstant(constant.MakeInt64(arg.Len), arg.mem), nil
case reflect.Chan:
arg.loadValue(loadFullValue)
if arg.Unreadable != nil {
return nil, arg.Unreadable
}
if arg.Base == 0 {
return newConstant(constant.MakeInt64(0), arg.mem), nil
}
return newConstant(arg.Children[0].Value, arg.mem), nil
case reflect.Map:
it := arg.mapIterator()
if arg.Unreadable != nil {
return nil, arg.Unreadable
}
if it == nil {
return newConstant(constant.MakeInt64(0), arg.mem), nil
}
return newConstant(constant.MakeInt64(arg.Len), arg.mem), nil
default:
return nil, invalidArgErr
}
}
func complexBuiltin(args []*Variable, nodeargs []ast.Expr) (*Variable, error) {
if len(args) != 2 {
return nil, fmt.Errorf("wrong number of arguments to complex: %d", len(args))
}
realev := args[0]
imagev := args[1]
realev.loadValue(loadSingleValue)
imagev.loadValue(loadSingleValue)
if realev.Unreadable != nil {
return nil, realev.Unreadable
}
if imagev.Unreadable != nil {
return nil, imagev.Unreadable
}
if realev.Value == nil || ((realev.Value.Kind() != constant.Int) && (realev.Value.Kind() != constant.Float)) {
return nil, fmt.Errorf("invalid argument 1 %s (type %s) to complex", exprToString(nodeargs[0]), realev.TypeString())
}
if imagev.Value == nil || ((imagev.Value.Kind() != constant.Int) && (imagev.Value.Kind() != constant.Float)) {
return nil, fmt.Errorf("invalid argument 2 %s (type %s) to complex", exprToString(nodeargs[1]), imagev.TypeString())
}
sz := int64(0)
if realev.RealType != nil {
sz = realev.RealType.(*dwarf.FloatType).Size()
}
if imagev.RealType != nil {
isz := imagev.RealType.(*dwarf.FloatType).Size()
if isz > sz {
sz = isz
}
}
if sz == 0 {
sz = 128
}
typ := &dwarf.ComplexType{BasicType: dwarf.BasicType{CommonType: dwarf.CommonType{ByteSize: int64(sz / 8), Name: fmt.Sprintf("complex%d", sz)}, BitSize: sz, BitOffset: 0}}
r := realev.newVariable("", 0, typ)
r.Value = constant.BinaryOp(realev.Value, token.ADD, constant.MakeImag(imagev.Value))
return r, nil
}
func imagBuiltin(args []*Variable, nodeargs []ast.Expr) (*Variable, error) {
if len(args) != 1 {
return nil, fmt.Errorf("wrong number of arguments to imag: %d", len(args))
}
arg := args[0]
arg.loadValue(loadSingleValue)
if arg.Unreadable != nil {
return nil, arg.Unreadable
}
if arg.Kind != reflect.Complex64 && arg.Kind != reflect.Complex128 {
return nil, fmt.Errorf("invalid argument %s (type %s) to imag", exprToString(nodeargs[0]), arg.TypeString())
}
return newConstant(constant.Imag(arg.Value), arg.mem), nil
}
func realBuiltin(args []*Variable, nodeargs []ast.Expr) (*Variable, error) {
if len(args) != 1 {
return nil, fmt.Errorf("wrong number of arguments to real: %d", len(args))
}
arg := args[0]
arg.loadValue(loadSingleValue)
if arg.Unreadable != nil {
return nil, arg.Unreadable
}
if arg.Value == nil || ((arg.Value.Kind() != constant.Int) && (arg.Value.Kind() != constant.Float) && (arg.Value.Kind() != constant.Complex)) {
return nil, fmt.Errorf("invalid argument %s (type %s) to real", exprToString(nodeargs[0]), arg.TypeString())
}
return newConstant(constant.Real(arg.Value), arg.mem), nil
}
// Evaluates identifier expressions
func (scope *EvalScope) evalIdent(node *ast.Ident) (*Variable, error) {
switch node.Name {
case "true", "false":
return newConstant(constant.MakeBool(node.Name == "true"), scope.Thread), nil
case "nil":
return nilVariable, nil
}
// try to interpret this as a local variable
v, err := scope.extractVarInfo(node.Name)
if err == nil {
return v, nil
}
origErr := err
// workaround: sometimes go inserts an entry for '&varname' instead of varname
v, err = scope.extractVarInfo("&" + node.Name)
if err == nil {
v = v.maybeDereference()
v.Name = node.Name
return v, nil
}
// if it's not a local variable then it could be a package variable w/o explicit package name
_, _, fn := scope.Thread.dbp.PCToLine(scope.PC)
if fn != nil {
if v, err = scope.packageVarAddr(fn.PackageName() + "." + node.Name); err == nil {
v.Name = node.Name
return v, nil
}
}
return nil, origErr
}
// Evaluates expressions <subexpr>.<field name> where subexpr is not a package name
func (scope *EvalScope) evalStructSelector(node *ast.SelectorExpr) (*Variable, error) {
xv, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
return xv.structMember(node.Sel.Name)
}
// Evaluates expressions <subexpr>.(<type>)
func (scope *EvalScope) evalTypeAssert(node *ast.TypeAssertExpr) (*Variable, error) {
xv, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
if xv.Kind != reflect.Interface {
return nil, fmt.Errorf("expression \"%s\" not an interface", exprToString(node.X))
}
xv.loadInterface(0, false, loadFullValue)
if xv.Unreadable != nil {
return nil, xv.Unreadable
}
if xv.Children[0].Unreadable != nil {
return nil, xv.Children[0].Unreadable
}
if xv.Children[0].Addr == 0 {
return nil, fmt.Errorf("interface conversion: %s is nil, not %s", xv.DwarfType.String(), exprToString(node.Type))
}
typ, err := scope.Thread.dbp.findTypeExpr(node.Type)
if err != nil {
return nil, err
}
if xv.Children[0].DwarfType.Common().Name != typ.Common().Name {
return nil, fmt.Errorf("interface conversion: %s is %s, not %s", xv.DwarfType.Common().Name, xv.Children[0].TypeString(), typ.Common().Name)
}
return &xv.Children[0], nil
}
// Evaluates expressions <subexpr>[<subexpr>] (subscript access to arrays, slices and maps)
func (scope *EvalScope) evalIndex(node *ast.IndexExpr) (*Variable, error) {
xev, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
if xev.Unreadable != nil {
return nil, xev.Unreadable
}
idxev, err := scope.evalAST(node.Index)
if err != nil {
return nil, err
}
switch xev.Kind {
case reflect.Slice, reflect.Array, reflect.String:
if xev.Base == 0 {
return nil, fmt.Errorf("can not index \"%s\"", exprToString(node.X))
}
n, err := idxev.asInt()
if err != nil {
return nil, err
}
return xev.sliceAccess(int(n))
case reflect.Map:
idxev.loadValue(loadFullValue)
if idxev.Unreadable != nil {
return nil, idxev.Unreadable
}
return xev.mapAccess(idxev)
default:
return nil, fmt.Errorf("expression \"%s\" (%s) does not support indexing", exprToString(node.X), xev.TypeString())
}
}
// Evaluates expressions <subexpr>[<subexpr>:<subexpr>]
// HACK: slicing a map expression with [0:0] will return the whole map
func (scope *EvalScope) evalReslice(node *ast.SliceExpr) (*Variable, error) {
xev, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
if xev.Unreadable != nil {
return nil, xev.Unreadable
}
var low, high int64
if node.Low != nil {
lowv, err := scope.evalAST(node.Low)
if err != nil {
return nil, err
}
low, err = lowv.asInt()
if err != nil {
return nil, fmt.Errorf("can not convert \"%s\" to int: %v", exprToString(node.Low), err)
}
}
if node.High == nil {
high = xev.Len
} else {
highv, err := scope.evalAST(node.High)
if err != nil {
return nil, err
}
high, err = highv.asInt()
if err != nil {
return nil, fmt.Errorf("can not convert \"%s\" to int: %v", exprToString(node.High), err)
}
}
switch xev.Kind {
case reflect.Slice, reflect.Array, reflect.String:
if xev.Base == 0 {
return nil, fmt.Errorf("can not slice \"%s\"", exprToString(node.X))
}
return xev.reslice(low, high)
case reflect.Map:
if node.High != nil {
return nil, fmt.Errorf("second slice argument must be empty for maps")
}
xev.mapSkip += int(low)
xev.loadValue(loadFullValue)
if xev.Unreadable != nil {
return nil, xev.Unreadable
}
return xev, nil
default:
return nil, fmt.Errorf("can not slice \"%s\" (type %s)", exprToString(node.X), xev.TypeString())
}
}
// Evaluates a pointer dereference expression: *<subexpr>
func (scope *EvalScope) evalPointerDeref(node *ast.StarExpr) (*Variable, error) {
xev, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
if xev.Kind != reflect.Ptr {
return nil, fmt.Errorf("expression \"%s\" (%s) can not be dereferenced", exprToString(node.X), xev.TypeString())
}
if xev == nilVariable {
return nil, fmt.Errorf("nil can not be dereferenced")
}
if len(xev.Children) == 1 {
// this branch is here to support pointers constructed with typecasts from ints
return &(xev.Children[0]), nil
}
rv := xev.maybeDereference()
if rv.Addr == 0 {
return nil, fmt.Errorf("nil pointer dereference")
}
return rv, nil
}
// Evaluates expressions &<subexpr>
func (scope *EvalScope) evalAddrOf(node *ast.UnaryExpr) (*Variable, error) {
xev, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
if xev.Addr == 0 || xev.DwarfType == nil {
return nil, fmt.Errorf("can not take address of \"%s\"", exprToString(node.X))
}
xev.OnlyAddr = true
typename := "*" + xev.DwarfType.Common().Name
rv := scope.newVariable("", 0, &dwarf.PtrType{CommonType: dwarf.CommonType{ByteSize: int64(scope.Thread.dbp.arch.PtrSize()), Name: typename}, Type: xev.DwarfType})
rv.Children = []Variable{*xev}
rv.loaded = true
return rv, nil
}
func constantUnaryOp(op token.Token, y constant.Value) (r constant.Value, err error) {
defer func() {
if ierr := recover(); ierr != nil {
err = fmt.Errorf("%v", ierr)
}
}()
r = constant.UnaryOp(op, y, 0)
return
}
func constantBinaryOp(op token.Token, x, y constant.Value) (r constant.Value, err error) {
defer func() {
if ierr := recover(); ierr != nil {
err = fmt.Errorf("%v", ierr)
}
}()
switch op {
case token.SHL, token.SHR:
n, _ := constant.Uint64Val(y)
r = constant.Shift(x, op, uint(n))
default:
r = constant.BinaryOp(x, op, y)
}
return
}
func constantCompare(op token.Token, x, y constant.Value) (r bool, err error) {
defer func() {
if ierr := recover(); ierr != nil {
err = fmt.Errorf("%v", ierr)
}
}()
r = constant.Compare(x, op, y)
return
}
// Evaluates expressions: -<subexpr> and +<subexpr>
func (scope *EvalScope) evalUnary(node *ast.UnaryExpr) (*Variable, error) {
xv, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
xv.loadValue(loadSingleValue)
if xv.Unreadable != nil {
return nil, xv.Unreadable
}
if xv.Value == nil {
return nil, fmt.Errorf("operator %s can not be applied to \"%s\"", node.Op.String(), exprToString(node.X))
}
rc, err := constantUnaryOp(node.Op, xv.Value)
if err != nil {
return nil, err
}
if xv.DwarfType != nil {
r := xv.newVariable("", 0, xv.DwarfType)
r.Value = rc
return r, nil
}
return newConstant(rc, xv.mem), nil
}
func negotiateType(op token.Token, xv, yv *Variable) (dwarf.Type, error) {
if xv == nilVariable {
return nil, negotiateTypeNil(op, yv)
}
if yv == nilVariable {
return nil, negotiateTypeNil(op, xv)
}
if op == token.SHR || op == token.SHL {
if xv.Value == nil || xv.Value.Kind() != constant.Int {
return nil, fmt.Errorf("shift of type %s", xv.Kind)
}
switch yv.Kind {
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
// ok
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
if yv.DwarfType != nil || constant.Sign(yv.Value) < 0 {
return nil, fmt.Errorf("shift count type %s, must be unsigned integer", yv.Kind.String())
}
default:
return nil, fmt.Errorf("shift count type %s, must be unsigned integer", yv.Kind.String())
}
return xv.DwarfType, nil
}
if xv.DwarfType == nil && yv.DwarfType == nil {
return nil, nil
}
if xv.DwarfType != nil && yv.DwarfType != nil {
if xv.DwarfType.String() != yv.DwarfType.String() {
return nil, fmt.Errorf("mismatched types \"%s\" and \"%s\"", xv.DwarfType.String(), yv.DwarfType.String())
}
return xv.DwarfType, nil
} else if xv.DwarfType != nil && yv.DwarfType == nil {
if err := yv.isType(xv.DwarfType, xv.Kind); err != nil {
return nil, err
}
return xv.DwarfType, nil
} else if xv.DwarfType == nil && yv.DwarfType != nil {
if err := xv.isType(yv.DwarfType, yv.Kind); err != nil {
return nil, err
}
return yv.DwarfType, nil
}
panic("unreachable")
}
func negotiateTypeNil(op token.Token, v *Variable) error {
if op != token.EQL && op != token.NEQ {
return fmt.Errorf("operator %s can not be applied to \"nil\"", op.String())
}
switch v.Kind {
case reflect.Ptr, reflect.UnsafePointer, reflect.Chan, reflect.Map, reflect.Interface, reflect.Slice, reflect.Func:
return nil
default:
return fmt.Errorf("can not compare %s to nil", v.Kind.String())
}
}
func (scope *EvalScope) evalBinary(node *ast.BinaryExpr) (*Variable, error) {
switch node.Op {
case token.INC, token.DEC, token.ARROW:
return nil, fmt.Errorf("operator %s not supported", node.Op.String())
}
xv, err := scope.evalAST(node.X)
if err != nil {
return nil, err
}
yv, err := scope.evalAST(node.Y)
if err != nil {
return nil, err
}
xv.loadValue(loadFullValue)
yv.loadValue(loadFullValue)
if xv.Unreadable != nil {
return nil, xv.Unreadable
}
if yv.Unreadable != nil {
return nil, yv.Unreadable
}
typ, err := negotiateType(node.Op, xv, yv)
if err != nil {
return nil, err
}
op := node.Op
if typ != nil && (op == token.QUO) {
_, isint := typ.(*dwarf.IntType)
_, isuint := typ.(*dwarf.UintType)
if isint || isuint {
// forces integer division if the result type is integer
op = token.QUO_ASSIGN
}
}
switch op {
case token.EQL, token.LSS, token.GTR, token.NEQ, token.LEQ, token.GEQ:
v, err := compareOp(op, xv, yv)
if err != nil {
return nil, err
}
return newConstant(constant.MakeBool(v), xv.mem), nil
default:
if xv.Value == nil {
return nil, fmt.Errorf("operator %s can not be applied to \"%s\"", node.Op.String(), exprToString(node.X))
}
if yv.Value == nil {
return nil, fmt.Errorf("operator %s can not be applied to \"%s\"", node.Op.String(), exprToString(node.Y))
}
rc, err := constantBinaryOp(op, xv.Value, yv.Value)
if err != nil {
return nil, err
}
if typ == nil {
return newConstant(rc, xv.mem), nil
}
r := xv.newVariable("", 0, typ)
r.Value = rc
return r, nil
}
}
// Comapres xv to yv using operator op
// Both xv and yv must be loaded and have a compatible type (as determined by negotiateType)
func compareOp(op token.Token, xv *Variable, yv *Variable) (bool, error) {
switch xv.Kind {
case reflect.Bool:
fallthrough
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
fallthrough
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
fallthrough
case reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
return constantCompare(op, xv.Value, yv.Value)
case reflect.String:
if int64(len(constant.StringVal(xv.Value))) != xv.Len || int64(len(constant.StringVal(yv.Value))) != yv.Len {
return false, fmt.Errorf("string too long for comparison")
}
return constantCompare(op, xv.Value, yv.Value)
}
if op != token.EQL && op != token.NEQ {
return false, fmt.Errorf("operator %s not defined on %s", op.String(), xv.Kind.String())
}
var eql bool
var err error
if xv == nilVariable {
switch op {
case token.EQL:
return yv.isNil(), nil
case token.NEQ:
return !yv.isNil(), nil
}
}
if yv == nilVariable {
switch op {
case token.EQL:
return xv.isNil(), nil
case token.NEQ:
return !xv.isNil(), nil
}
}
switch xv.Kind {
case reflect.Ptr:
eql = xv.Children[0].Addr == yv.Children[0].Addr
case reflect.Array:
if int64(len(xv.Children)) != xv.Len || int64(len(yv.Children)) != yv.Len {
return false, fmt.Errorf("array too long for comparison")
}
eql, err = equalChildren(xv, yv, true)
case reflect.Struct:
if len(xv.Children) != len(yv.Children) {
return false, nil
}
if int64(len(xv.Children)) != xv.Len || int64(len(yv.Children)) != yv.Len {
return false, fmt.Errorf("sturcture too deep for comparison")
}
eql, err = equalChildren(xv, yv, false)
case reflect.Slice, reflect.Map, reflect.Func, reflect.Chan:
return false, fmt.Errorf("can not compare %s variables", xv.Kind.String())
case reflect.Interface:
if xv.Children[0].RealType.String() != yv.Children[0].RealType.String() {
eql = false
} else {
eql, err = compareOp(token.EQL, &xv.Children[0], &yv.Children[0])
}
default:
return false, fmt.Errorf("unimplemented comparison of %s variables", xv.Kind.String())
}
if op == token.NEQ {
return !eql, err
}
return eql, err
}
func (v *Variable) isNil() bool {
switch v.Kind {
case reflect.Ptr:
return v.Children[0].Addr == 0
case reflect.Interface:
return false
case reflect.Slice, reflect.Map, reflect.Func, reflect.Chan:
return v.Base == 0
}
return false
}
func equalChildren(xv, yv *Variable, shortcircuit bool) (bool, error) {
r := true
for i := range xv.Children {
eql, err := compareOp(token.EQL, &xv.Children[i], &yv.Children[i])
if err != nil {
return false, err
}
r = r && eql
if !r && shortcircuit {
return false, nil
}
}
return r, nil
}
func (v *Variable) asInt() (int64, error) {
if v.DwarfType == nil {
if v.Value.Kind() != constant.Int {
return 0, fmt.Errorf("can not convert constant %s to int", v.Value)
}
} else {
v.loadValue(loadSingleValue)
if v.Unreadable != nil {
return 0, v.Unreadable
}
if _, ok := v.DwarfType.(*dwarf.IntType); !ok {
return 0, fmt.Errorf("can not convert value of type %s to int", v.DwarfType.String())
}
}
n, _ := constant.Int64Val(v.Value)
return n, nil
}
func (v *Variable) asUint() (uint64, error) {
if v.DwarfType == nil {
if v.Value.Kind() != constant.Int {
return 0, fmt.Errorf("can not convert constant %s to uint", v.Value)
}
} else {
v.loadValue(loadSingleValue)
if v.Unreadable != nil {
return 0, v.Unreadable
}
if _, ok := v.DwarfType.(*dwarf.UintType); !ok {
return 0, fmt.Errorf("can not convert value of type %s to uint", v.DwarfType.String())
}
}
n, _ := constant.Uint64Val(v.Value)
return n, nil
}
func (v *Variable) isType(typ dwarf.Type, kind reflect.Kind) error {
if v.DwarfType != nil {
if typ != nil && typ.String() != v.RealType.String() {
return fmt.Errorf("can not convert value of type %s to %s", v.DwarfType.String(), typ.String())
}
return nil
}
if typ == nil {
return nil
}
if v == nilVariable {
switch kind {
case reflect.Slice, reflect.Map, reflect.Func, reflect.Ptr, reflect.Chan, reflect.Interface:
return nil
default:
return fmt.Errorf("mismatched types nil and %s", typ.String())
}
}
converr := fmt.Errorf("can not convert %s constant to %s", v.Value, typ.String())
if v.Value == nil {
return converr
}
switch typ.(type) {
case *dwarf.IntType:
if v.Value.Kind() != constant.Int {
return converr
}
case *dwarf.UintType:
if v.Value.Kind() != constant.Int {
return converr
}
case *dwarf.FloatType:
if (v.Value.Kind() != constant.Int) && (v.Value.Kind() != constant.Float) {
return converr
}
case *dwarf.BoolType:
if v.Value.Kind() != constant.Bool {
return converr
}
case *dwarf.StringType:
if v.Value.Kind() != constant.String {
return converr
}
case *dwarf.ComplexType:
if v.Value.Kind() != constant.Complex && v.Value.Kind() != constant.Float && v.Value.Kind() != constant.Int {
return converr
}
default:
return converr
}
return nil
}
func (v *Variable) sliceAccess(idx int) (*Variable, error) {
if idx < 0 || int64(idx) >= v.Len {
return nil, fmt.Errorf("index out of bounds")
}
return v.newVariable("", v.Base+uintptr(int64(idx)*v.stride), v.fieldType), nil
}
func (v *Variable) mapAccess(idx *Variable) (*Variable, error) {
it := v.mapIterator()
if it == nil {
return nil, fmt.Errorf("can not access unreadable map: %v", v.Unreadable)
}
first := true
for it.next() {
key := it.key()
key.loadValue(loadFullValue)
if key.Unreadable != nil {
return nil, fmt.Errorf("can not access unreadable map: %v", key.Unreadable)
}
if first {
first = false
if err := idx.isType(key.DwarfType, key.Kind); err != nil {
return nil, err
}
}
eql, err := compareOp(token.EQL, key, idx)
if err != nil {
return nil, err
}
if eql {
return it.value(), nil
}
}
if v.Unreadable != nil {
return nil, v.Unreadable
}
// go would return zero for the map value type here, we do not have the ability to create zeroes
return nil, fmt.Errorf("key not found")
}
func (v *Variable) reslice(low int64, high int64) (*Variable, error) {
if low < 0 || low >= v.Len || high < 0 || high > v.Len {
return nil, fmt.Errorf("index out of bounds")
}
base := v.Base + uintptr(int64(low)*v.stride)
len := high - low
if high-low < 0 {
return nil, fmt.Errorf("index out of bounds")
}
typ := v.DwarfType
if _, isarr := v.DwarfType.(*dwarf.ArrayType); isarr {
typ = &dwarf.SliceType{
StructType: dwarf.StructType{
CommonType: dwarf.CommonType{
ByteSize: 24,
Name: "",
},
StructName: fmt.Sprintf("[]%s", v.fieldType.Common().Name),
Kind: "struct",
Field: nil,
},
ElemType: v.fieldType,
}
}
r := v.newVariable("", 0, typ)
r.Cap = len
r.Len = len
r.Base = base
r.stride = v.stride
r.fieldType = v.fieldType
return r, nil
}