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// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package interp
import (
"bytes"
"fmt"
"go/constant"
"go/token"
"go/types"
"os"
"strings"
"sync"
"unsafe"
"golang.org/x/tools/go/ssa"
)
// If the target program panics, the interpreter panics with this type.
type targetPanic struct {
v value
}
func (p targetPanic) String() string {
return toString(p.v)
}
// If the target program calls exit, the interpreter panics with this type.
type exitPanic int
// constValue returns the value of the constant with the
// dynamic type tag appropriate for c.Type().
func constValue(c *ssa.Const) value {
if c.IsNil() {
return zero(c.Type()) // typed nil
}
if t, ok := c.Type().Underlying().(*types.Basic); ok {
// TODO(adonovan): eliminate untyped constants from SSA form.
switch t.Kind() {
case types.Bool, types.UntypedBool:
return constant.BoolVal(c.Value)
case types.Int, types.UntypedInt:
// Assume sizeof(int) is same on host and target.
return int(c.Int64())
case types.Int8:
return int8(c.Int64())
case types.Int16:
return int16(c.Int64())
case types.Int32, types.UntypedRune:
return int32(c.Int64())
case types.Int64:
return c.Int64()
case types.Uint:
// Assume sizeof(uint) is same on host and target.
return uint(c.Uint64())
case types.Uint8:
return uint8(c.Uint64())
case types.Uint16:
return uint16(c.Uint64())
case types.Uint32:
return uint32(c.Uint64())
case types.Uint64:
return c.Uint64()
case types.Uintptr:
// Assume sizeof(uintptr) is same on host and target.
return uintptr(c.Uint64())
case types.Float32:
return float32(c.Float64())
case types.Float64, types.UntypedFloat:
return c.Float64()
case types.Complex64:
return complex64(c.Complex128())
case types.Complex128, types.UntypedComplex:
return c.Complex128()
case types.String, types.UntypedString:
if c.Value.Kind() == constant.String {
return constant.StringVal(c.Value)
}
return string(rune(c.Int64()))
}
}
panic(fmt.Sprintf("constValue: %s", c))
}
// asInt converts x, which must be an integer, to an int suitable for
// use as a slice or array index or operand to make().
func asInt(x value) int {
switch x := x.(type) {
case int:
return x
case int8:
return int(x)
case int16:
return int(x)
case int32:
return int(x)
case int64:
return int(x)
case uint:
return int(x)
case uint8:
return int(x)
case uint16:
return int(x)
case uint32:
return int(x)
case uint64:
return int(x)
case uintptr:
return int(x)
}
panic(fmt.Sprintf("cannot convert %T to int", x))
}
// asUint64 converts x, which must be an unsigned integer, to a uint64
// suitable for use as a bitwise shift count.
func asUint64(x value) uint64 {
switch x := x.(type) {
case uint:
return uint64(x)
case uint8:
return uint64(x)
case uint16:
return uint64(x)
case uint32:
return uint64(x)
case uint64:
return x
case uintptr:
return uint64(x)
}
panic(fmt.Sprintf("cannot convert %T to uint64", x))
}
// zero returns a new "zero" value of the specified type.
func zero(t types.Type) value {
switch t := t.(type) {
case *types.Basic:
if t.Kind() == types.UntypedNil {
panic("untyped nil has no zero value")
}
if t.Info()&types.IsUntyped != 0 {
// TODO(adonovan): make it an invariant that
// this is unreachable. Currently some
// constants have 'untyped' types when they
// should be defaulted by the typechecker.
t = ssa.DefaultType(t).(*types.Basic)
}
switch t.Kind() {
case types.Bool:
return false
case types.Int:
return int(0)
case types.Int8:
return int8(0)
case types.Int16:
return int16(0)
case types.Int32:
return int32(0)
case types.Int64:
return int64(0)
case types.Uint:
return uint(0)
case types.Uint8:
return uint8(0)
case types.Uint16:
return uint16(0)
case types.Uint32:
return uint32(0)
case types.Uint64:
return uint64(0)
case types.Uintptr:
return uintptr(0)
case types.Float32:
return float32(0)
case types.Float64:
return float64(0)
case types.Complex64:
return complex64(0)
case types.Complex128:
return complex128(0)
case types.String:
return ""
case types.UnsafePointer:
return unsafe.Pointer(nil)
default:
panic(fmt.Sprint("zero for unexpected type:", t))
}
case *types.Pointer:
return (*value)(nil)
case *types.Array:
a := make(array, t.Len())
for i := range a {
a[i] = zero(t.Elem())
}
return a
case *types.Named:
return zero(t.Underlying())
case *types.Interface:
return iface{} // nil type, methodset and value
case *types.Slice:
return []value(nil)
case *types.Struct:
s := make(structure, t.NumFields())
for i := range s {
s[i] = zero(t.Field(i).Type())
}
return s
case *types.Tuple:
if t.Len() == 1 {
return zero(t.At(0).Type())
}
s := make(tuple, t.Len())
for i := range s {
s[i] = zero(t.At(i).Type())
}
return s
case *types.Chan:
return chan value(nil)
case *types.Map:
if usesBuiltinMap(t.Key()) {
return map[value]value(nil)
}
return (*hashmap)(nil)
case *types.Signature:
return (*ssa.Function)(nil)
}
panic(fmt.Sprint("zero: unexpected ", t))
}
// slice returns x[lo:hi:max]. Any of lo, hi and max may be nil.
func slice(x, lo, hi, max value) value {
var Len, Cap int
switch x := x.(type) {
case string:
Len = len(x)
case []value:
Len = len(x)
Cap = cap(x)
case *value: // *array
a := (*x).(array)
Len = len(a)
Cap = cap(a)
}
l := 0
if lo != nil {
l = asInt(lo)
}
h := Len
if hi != nil {
h = asInt(hi)
}
m := Cap
if max != nil {
m = asInt(max)
}
switch x := x.(type) {
case string:
return x[l:h]
case []value:
return x[l:h:m]
case *value: // *array
a := (*x).(array)
return []value(a)[l:h:m]
}
panic(fmt.Sprintf("slice: unexpected X type: %T", x))
}
// lookup returns x[idx] where x is a map or string.
func lookup(instr *ssa.Lookup, x, idx value) value {
switch x := x.(type) { // map or string
case map[value]value, *hashmap:
var v value
var ok bool
switch x := x.(type) {
case map[value]value:
v, ok = x[idx]
case *hashmap:
v = x.lookup(idx.(hashable))
ok = v != nil
}
if !ok {
v = zero(instr.X.Type().Underlying().(*types.Map).Elem())
}
if instr.CommaOk {
v = tuple{v, ok}
}
return v
case string:
return x[asInt(idx)]
}
panic(fmt.Sprintf("unexpected x type in Lookup: %T", x))
}
// binop implements all arithmetic and logical binary operators for
// numeric datatypes and strings. Both operands must have identical
// dynamic type.
//
func binop(op token.Token, t types.Type, x, y value) value {
switch op {
case token.ADD:
switch x.(type) {
case int:
return x.(int) + y.(int)
case int8:
return x.(int8) + y.(int8)
case int16:
return x.(int16) + y.(int16)
case int32:
return x.(int32) + y.(int32)
case int64:
return x.(int64) + y.(int64)
case uint:
return x.(uint) + y.(uint)
case uint8:
return x.(uint8) + y.(uint8)
case uint16:
return x.(uint16) + y.(uint16)
case uint32:
return x.(uint32) + y.(uint32)
case uint64:
return x.(uint64) + y.(uint64)
case uintptr:
return x.(uintptr) + y.(uintptr)
case float32:
return x.(float32) + y.(float32)
case float64:
return x.(float64) + y.(float64)
case complex64:
return x.(complex64) + y.(complex64)
case complex128:
return x.(complex128) + y.(complex128)
case string:
return x.(string) + y.(string)
}
case token.SUB:
switch x.(type) {
case int:
return x.(int) - y.(int)
case int8:
return x.(int8) - y.(int8)
case int16:
return x.(int16) - y.(int16)
case int32:
return x.(int32) - y.(int32)
case int64:
return x.(int64) - y.(int64)
case uint:
return x.(uint) - y.(uint)
case uint8:
return x.(uint8) - y.(uint8)
case uint16:
return x.(uint16) - y.(uint16)
case uint32:
return x.(uint32) - y.(uint32)
case uint64:
return x.(uint64) - y.(uint64)
case uintptr:
return x.(uintptr) - y.(uintptr)
case float32:
return x.(float32) - y.(float32)
case float64:
return x.(float64) - y.(float64)
case complex64:
return x.(complex64) - y.(complex64)
case complex128:
return x.(complex128) - y.(complex128)
}
case token.MUL:
switch x.(type) {
case int:
return x.(int) * y.(int)
case int8:
return x.(int8) * y.(int8)
case int16:
return x.(int16) * y.(int16)
case int32:
return x.(int32) * y.(int32)
case int64:
return x.(int64) * y.(int64)
case uint:
return x.(uint) * y.(uint)
case uint8:
return x.(uint8) * y.(uint8)
case uint16:
return x.(uint16) * y.(uint16)
case uint32:
return x.(uint32) * y.(uint32)
case uint64:
return x.(uint64) * y.(uint64)
case uintptr:
return x.(uintptr) * y.(uintptr)
case float32:
return x.(float32) * y.(float32)
case float64:
return x.(float64) * y.(float64)
case complex64:
return x.(complex64) * y.(complex64)
case complex128:
return x.(complex128) * y.(complex128)
}
case token.QUO:
switch x.(type) {
case int:
return x.(int) / y.(int)
case int8:
return x.(int8) / y.(int8)
case int16:
return x.(int16) / y.(int16)
case int32:
return x.(int32) / y.(int32)
case int64:
return x.(int64) / y.(int64)
case uint:
return x.(uint) / y.(uint)
case uint8:
return x.(uint8) / y.(uint8)
case uint16:
return x.(uint16) / y.(uint16)
case uint32:
return x.(uint32) / y.(uint32)
case uint64:
return x.(uint64) / y.(uint64)
case uintptr:
return x.(uintptr) / y.(uintptr)
case float32:
return x.(float32) / y.(float32)
case float64:
return x.(float64) / y.(float64)
case complex64:
return x.(complex64) / y.(complex64)
case complex128:
return x.(complex128) / y.(complex128)
}
case token.REM:
switch x.(type) {
case int:
return x.(int) % y.(int)
case int8:
return x.(int8) % y.(int8)
case int16:
return x.(int16) % y.(int16)
case int32:
return x.(int32) % y.(int32)
case int64:
return x.(int64) % y.(int64)
case uint:
return x.(uint) % y.(uint)
case uint8:
return x.(uint8) % y.(uint8)
case uint16:
return x.(uint16) % y.(uint16)
case uint32:
return x.(uint32) % y.(uint32)
case uint64:
return x.(uint64) % y.(uint64)
case uintptr:
return x.(uintptr) % y.(uintptr)
}
case token.AND:
switch x.(type) {
case int:
return x.(int) & y.(int)
case int8:
return x.(int8) & y.(int8)
case int16:
return x.(int16) & y.(int16)
case int32:
return x.(int32) & y.(int32)
case int64:
return x.(int64) & y.(int64)
case uint:
return x.(uint) & y.(uint)
case uint8:
return x.(uint8) & y.(uint8)
case uint16:
return x.(uint16) & y.(uint16)
case uint32:
return x.(uint32) & y.(uint32)
case uint64:
return x.(uint64) & y.(uint64)
case uintptr:
return x.(uintptr) & y.(uintptr)
}
case token.OR:
switch x.(type) {
case int:
return x.(int) | y.(int)
case int8:
return x.(int8) | y.(int8)
case int16:
return x.(int16) | y.(int16)
case int32:
return x.(int32) | y.(int32)
case int64:
return x.(int64) | y.(int64)
case uint:
return x.(uint) | y.(uint)
case uint8:
return x.(uint8) | y.(uint8)
case uint16:
return x.(uint16) | y.(uint16)
case uint32:
return x.(uint32) | y.(uint32)
case uint64:
return x.(uint64) | y.(uint64)
case uintptr:
return x.(uintptr) | y.(uintptr)
}
case token.XOR:
switch x.(type) {
case int:
return x.(int) ^ y.(int)
case int8:
return x.(int8) ^ y.(int8)
case int16:
return x.(int16) ^ y.(int16)
case int32:
return x.(int32) ^ y.(int32)
case int64:
return x.(int64) ^ y.(int64)
case uint:
return x.(uint) ^ y.(uint)
case uint8:
return x.(uint8) ^ y.(uint8)
case uint16:
return x.(uint16) ^ y.(uint16)
case uint32:
return x.(uint32) ^ y.(uint32)
case uint64:
return x.(uint64) ^ y.(uint64)
case uintptr:
return x.(uintptr) ^ y.(uintptr)
}
case token.AND_NOT:
switch x.(type) {
case int:
return x.(int) &^ y.(int)
case int8:
return x.(int8) &^ y.(int8)
case int16:
return x.(int16) &^ y.(int16)
case int32:
return x.(int32) &^ y.(int32)
case int64:
return x.(int64) &^ y.(int64)
case uint:
return x.(uint) &^ y.(uint)
case uint8:
return x.(uint8) &^ y.(uint8)
case uint16:
return x.(uint16) &^ y.(uint16)
case uint32:
return x.(uint32) &^ y.(uint32)
case uint64:
return x.(uint64) &^ y.(uint64)
case uintptr:
return x.(uintptr) &^ y.(uintptr)
}
case token.SHL:
y := asUint64(y)
switch x.(type) {
case int:
return x.(int) << y
case int8:
return x.(int8) << y
case int16:
return x.(int16) << y
case int32:
return x.(int32) << y
case int64:
return x.(int64) << y
case uint:
return x.(uint) << y
case uint8:
return x.(uint8) << y
case uint16:
return x.(uint16) << y
case uint32:
return x.(uint32) << y
case uint64:
return x.(uint64) << y
case uintptr:
return x.(uintptr) << y
}
case token.SHR:
y := asUint64(y)
switch x.(type) {
case int:
return x.(int) >> y
case int8:
return x.(int8) >> y
case int16:
return x.(int16) >> y
case int32:
return x.(int32) >> y
case int64:
return x.(int64) >> y
case uint:
return x.(uint) >> y
case uint8:
return x.(uint8) >> y
case uint16:
return x.(uint16) >> y
case uint32:
return x.(uint32) >> y
case uint64:
return x.(uint64) >> y
case uintptr:
return x.(uintptr) >> y
}
case token.LSS:
switch x.(type) {
case int:
return x.(int) < y.(int)
case int8:
return x.(int8) < y.(int8)
case int16:
return x.(int16) < y.(int16)
case int32:
return x.(int32) < y.(int32)
case int64:
return x.(int64) < y.(int64)
case uint:
return x.(uint) < y.(uint)
case uint8:
return x.(uint8) < y.(uint8)
case uint16:
return x.(uint16) < y.(uint16)
case uint32:
return x.(uint32) < y.(uint32)
case uint64:
return x.(uint64) < y.(uint64)
case uintptr:
return x.(uintptr) < y.(uintptr)
case float32:
return x.(float32) < y.(float32)
case float64:
return x.(float64) < y.(float64)
case string:
return x.(string) < y.(string)
}
case token.LEQ:
switch x.(type) {
case int:
return x.(int) <= y.(int)
case int8:
return x.(int8) <= y.(int8)
case int16:
return x.(int16) <= y.(int16)
case int32:
return x.(int32) <= y.(int32)
case int64:
return x.(int64) <= y.(int64)
case uint:
return x.(uint) <= y.(uint)
case uint8:
return x.(uint8) <= y.(uint8)
case uint16:
return x.(uint16) <= y.(uint16)
case uint32:
return x.(uint32) <= y.(uint32)
case uint64:
return x.(uint64) <= y.(uint64)
case uintptr:
return x.(uintptr) <= y.(uintptr)
case float32:
return x.(float32) <= y.(float32)
case float64:
return x.(float64) <= y.(float64)
case string:
return x.(string) <= y.(string)
}
case token.EQL:
return eqnil(t, x, y)
case token.NEQ:
return !eqnil(t, x, y)
case token.GTR:
switch x.(type) {
case int:
return x.(int) > y.(int)
case int8:
return x.(int8) > y.(int8)
case int16:
return x.(int16) > y.(int16)
case int32:
return x.(int32) > y.(int32)
case int64:
return x.(int64) > y.(int64)
case uint:
return x.(uint) > y.(uint)
case uint8:
return x.(uint8) > y.(uint8)
case uint16:
return x.(uint16) > y.(uint16)
case uint32:
return x.(uint32) > y.(uint32)
case uint64:
return x.(uint64) > y.(uint64)
case uintptr:
return x.(uintptr) > y.(uintptr)
case float32:
return x.(float32) > y.(float32)
case float64:
return x.(float64) > y.(float64)
case string:
return x.(string) > y.(string)
}
case token.GEQ:
switch x.(type) {
case int:
return x.(int) >= y.(int)
case int8:
return x.(int8) >= y.(int8)
case int16:
return x.(int16) >= y.(int16)
case int32:
return x.(int32) >= y.(int32)
case int64:
return x.(int64) >= y.(int64)
case uint:
return x.(uint) >= y.(uint)
case uint8:
return x.(uint8) >= y.(uint8)
case uint16:
return x.(uint16) >= y.(uint16)
case uint32:
return x.(uint32) >= y.(uint32)
case uint64:
return x.(uint64) >= y.(uint64)
case uintptr:
return x.(uintptr) >= y.(uintptr)
case float32:
return x.(float32) >= y.(float32)
case float64:
return x.(float64) >= y.(float64)
case string:
return x.(string) >= y.(string)
}
}
panic(fmt.Sprintf("invalid binary op: %T %s %T", x, op, y))
}
// eqnil returns the comparison x == y using the equivalence relation
// appropriate for type t.
// If t is a reference type, at most one of x or y may be a nil value
// of that type.
//
func eqnil(t types.Type, x, y value) bool {
switch t.Underlying().(type) {
case *types.Map, *types.Signature, *types.Slice:
// Since these types don't support comparison,
// one of the operands must be a literal nil.
switch x := x.(type) {
case *hashmap:
return (x != nil) == (y.(*hashmap) != nil)
case map[value]value:
return (x != nil) == (y.(map[value]value) != nil)
case *ssa.Function:
switch y := y.(type) {
case *ssa.Function:
return (x != nil) == (y != nil)
case *closure:
return true
}
case *closure:
return (x != nil) == (y.(*ssa.Function) != nil)
case []value:
return (x != nil) == (y.([]value) != nil)
}
panic(fmt.Sprintf("eqnil(%s): illegal dynamic type: %T", t, x))
}
return equals(t, x, y)
}
func unop(instr *ssa.UnOp, x value) value {
switch instr.Op {
case token.ARROW: // receive
v, ok := <-x.(chan value)
if !ok {
v = zero(instr.X.Type().Underlying().(*types.Chan).Elem())
}
if instr.CommaOk {
v = tuple{v, ok}
}
return v
case token.SUB:
switch x := x.(type) {
case int:
return -x
case int8:
return -x
case int16:
return -x
case int32:
return -x
case int64:
return -x
case uint:
return -x
case uint8:
return -x
case uint16:
return -x
case uint32:
return -x
case uint64:
return -x
case uintptr:
return -x
case float32:
return -x
case float64:
return -x
case complex64:
return -x
case complex128:
return -x
}
case token.MUL:
return load(deref(instr.X.Type()), x.(*value))
case token.NOT:
return !x.(bool)
case token.XOR:
switch x := x.(type) {
case int:
return ^x
case int8:
return ^x
case int16:
return ^x
case int32:
return ^x
case int64:
return ^x
case uint:
return ^x
case uint8:
return ^x
case uint16:
return ^x
case uint32:
return ^x
case uint64:
return ^x
case uintptr:
return ^x
}
}
panic(fmt.Sprintf("invalid unary op %s %T", instr.Op, x))
}
// typeAssert checks whether dynamic type of itf is instr.AssertedType.
// It returns the extracted value on success, and panics on failure,
// unless instr.CommaOk, in which case it always returns a "value,ok" tuple.
//
func typeAssert(i *interpreter, instr *ssa.TypeAssert, itf iface) value {
var v value
err := ""
if itf.t == nil {
err = fmt.Sprintf("interface conversion: interface is nil, not %s", instr.AssertedType)
} else if idst, ok := instr.AssertedType.Underlying().(*types.Interface); ok {
v = itf
err = checkInterface(i, idst, itf)
} else if types.Identical(itf.t, instr.AssertedType) {
v = itf.v // extract value
} else {
err = fmt.Sprintf("interface conversion: interface is %s, not %s", itf.t, instr.AssertedType)
}
if err != "" {
if !instr.CommaOk {
panic(err)
}
return tuple{zero(instr.AssertedType), false}
}
if instr.CommaOk {
return tuple{v, true}
}
return v
}
// If CapturedOutput is non-nil, all writes by the interpreted program
// to file descriptors 1 and 2 will also be written to CapturedOutput.
//
// (The $GOROOT/test system requires that the test be considered a
// failure if "BUG" appears in the combined stdout/stderr output, even
// if it exits zero. This is a global variable shared by all
// interpreters in the same process.)
//
var CapturedOutput *bytes.Buffer
var capturedOutputMu sync.Mutex
// write writes bytes b to the target program's standard output.
// The print/println built-ins and the write() system call funnel
// through here so they can be captured by the test driver.
func print(b []byte) (int, error) {
if CapturedOutput != nil {
capturedOutputMu.Lock()
CapturedOutput.Write(b) // ignore errors
capturedOutputMu.Unlock()
}
return os.Stdout.Write(b)
}
// callBuiltin interprets a call to builtin fn with arguments args,
// returning its result.
func callBuiltin(caller *frame, callpos token.Pos, fn *ssa.Builtin, args []value) value {
switch fn.Name() {
case "append":
if len(args) == 1 {
return args[0]
}
if s, ok := args[1].(string); ok {
// append([]byte, ...string) []byte
arg0 := args[0].([]value)
for i := 0; i < len(s); i++ {
arg0 = append(arg0, s[i])
}
return arg0
}
// append([]T, ...[]T) []T
return append(args[0].([]value), args[1].([]value)...)
case "copy": // copy([]T, []T) int or copy([]byte, string) int
src := args[1]
if _, ok := src.(string); ok {
params := fn.Type().(*types.Signature).Params()
src = conv(params.At(0).Type(), params.At(1).Type(), src)
}
return copy(args[0].([]value), src.([]value))
case "close": // close(chan T)
close(args[0].(chan value))
return nil
case "delete": // delete(map[K]value, K)
switch m := args[0].(type) {
case map[value]value:
delete(m, args[1])
case *hashmap:
m.delete(args[1].(hashable))
default:
panic(fmt.Sprintf("illegal map type: %T", m))
}
return nil
case "print", "println": // print(any, ...)
ln := fn.Name() == "println"
var buf bytes.Buffer
for i, arg := range args {
if i > 0 && ln {
buf.WriteRune(' ')
}
buf.WriteString(toString(arg))
}
if ln {
buf.WriteRune('\n')
}
print(buf.Bytes())
return nil
case "len":
switch x := args[0].(type) {
case string:
return len(x)
case array:
return len(x)
case *value:
return len((*x).(array))
case []value:
return len(x)
case map[value]value:
return len(x)
case *hashmap:
return x.len()
case chan value:
return len(x)
default:
panic(fmt.Sprintf("len: illegal operand: %T", x))
}
case "cap":
switch x := args[0].(type) {
case array:
return cap(x)
case *value:
return cap((*x).(array))
case []value:
return cap(x)
case chan value:
return cap(x)
default:
panic(fmt.Sprintf("cap: illegal operand: %T", x))
}
case "real":
switch c := args[0].(type) {
case complex64:
return real(c)
case complex128:
return real(c)
default:
panic(fmt.Sprintf("real: illegal operand: %T", c))
}
case "imag":
switch c := args[0].(type) {
case complex64:
return imag(c)
case complex128:
return imag(c)
default:
panic(fmt.Sprintf("imag: illegal operand: %T", c))
}
case "complex":
switch f := args[0].(type) {
case float32:
return complex(f, args[1].(float32))
case float64:
return complex(f, args[1].(float64))
default:
panic(fmt.Sprintf("complex: illegal operand: %T", f))
}
case "panic":
// ssa.Panic handles most cases; this is only for "go
// panic" or "defer panic".
panic(targetPanic{args[0]})
case "recover":
return doRecover(caller)
case "ssa:wrapnilchk":
recv := args[0]
if recv.(*value) == nil {
recvType := args[1]
methodName := args[2]
panic(fmt.Sprintf("value method (%s).%s called using nil *%s pointer",
recvType, methodName, recvType))
}
return recv
}
panic("unknown built-in: " + fn.Name())
}
func rangeIter(x value, t types.Type) iter {
switch x := x.(type) {
case map[value]value:
// TODO(adonovan): fix: leaks goroutines and channels
// on each incomplete map iteration. We need to open
// up an iteration interface using the
// reflect.(Value).MapKeys machinery.
it := make(mapIter)
go func() {
for k, v := range x {
it <- [2]value{k, v}
}
close(it)
}()
return it
case *hashmap:
// TODO(adonovan): fix: leaks goroutines and channels
// on each incomplete map iteration. We need to open
// up an iteration interface using the
// reflect.(Value).MapKeys machinery.
it := make(mapIter)
go func() {
for _, e := range x.entries() {
for e != nil {
it <- [2]value{e.key, e.value}
e = e.next
}
}
close(it)
}()
return it
case string:
return &stringIter{Reader: strings.NewReader(x)}
}
panic(fmt.Sprintf("cannot range over %T", x))
}
// widen widens a basic typed value x to the widest type of its
// category, one of:
// bool, int64, uint64, float64, complex128, string.
// This is inefficient but reduces the size of the cross-product of
// cases we have to consider.
//
func widen(x value) value {
switch y := x.(type) {
case bool, int64, uint64, float64, complex128, string, unsafe.Pointer:
return x
case int:
return int64(y)
case int8:
return int64(y)
case int16:
return int64(y)
case int32:
return int64(y)
case uint:
return uint64(y)
case uint8:
return uint64(y)
case uint16:
return uint64(y)
case uint32:
return uint64(y)
case uintptr:
return uint64(y)
case float32:
return float64(y)
case complex64:
return complex128(y)
}
panic(fmt.Sprintf("cannot widen %T", x))
}
// conv converts the value x of type t_src to type t_dst and returns
// the result.
// Possible cases are described with the ssa.Convert operator.
//
func conv(t_dst, t_src types.Type, x value) value {
ut_src := t_src.Underlying()
ut_dst := t_dst.Underlying()
// Destination type is not an "untyped" type.
if b, ok := ut_dst.(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
panic("oops: conversion to 'untyped' type: " + b.String())
}
// Nor is it an interface type.
if _, ok := ut_dst.(*types.Interface); ok {
if _, ok := ut_src.(*types.Interface); ok {
panic("oops: Convert should be ChangeInterface")
} else {
panic("oops: Convert should be MakeInterface")
}
}
// Remaining conversions:
// + untyped string/number/bool constant to a specific
// representation.
// + conversions between non-complex numeric types.
// + conversions between complex numeric types.
// + integer/[]byte/[]rune -> string.
// + string -> []byte/[]rune.
//
// All are treated the same: first we extract the value to the
// widest representation (int64, uint64, float64, complex128,
// or string), then we convert it to the desired type.
switch ut_src := ut_src.(type) {
case *types.Pointer:
switch ut_dst := ut_dst.(type) {
case *types.Basic:
// *value to unsafe.Pointer?
if ut_dst.Kind() == types.UnsafePointer {
return unsafe.Pointer(x.(*value))
}
}
case *types.Slice:
// []byte or []rune -> string
// TODO(adonovan): fix: type B byte; conv([]B -> string).
switch ut_src.Elem().(*types.Basic).Kind() {
case types.Byte:
x := x.([]value)
b := make([]byte, 0, len(x))
for i := range x {
b = append(b, x[i].(byte))
}
return string(b)
case types.Rune:
x := x.([]value)
r := make([]rune, 0, len(x))
for i := range x {
r = append(r, x[i].(rune))
}
return string(r)
}
case *types.Basic:
x = widen(x)
// integer -> string?
// TODO(adonovan): fix: test integer -> named alias of string.
if ut_src.Info()&types.IsInteger != 0 {
if ut_dst, ok := ut_dst.(*types.Basic); ok && ut_dst.Kind() == types.String {
return string(asInt(x))
}
}
// string -> []rune, []byte or string?
if s, ok := x.(string); ok {
switch ut_dst := ut_dst.(type) {
case *types.Slice:
var res []value
// TODO(adonovan): fix: test named alias of rune, byte.
switch ut_dst.Elem().(*types.Basic).Kind() {
case types.Rune:
for _, r := range []rune(s) {
res = append(res, r)
}
return res
case types.Byte:
for _, b := range []byte(s) {
res = append(res, b)
}
return res
}
case *types.Basic:
if ut_dst.Kind() == types.String {
return x.(string)
}
}
break // fail: no other conversions for string
}
// unsafe.Pointer -> *value
if ut_src.Kind() == types.UnsafePointer {
// TODO(adonovan): this is wrong and cannot
// really be fixed with the current design.
//
// return (*value)(x.(unsafe.Pointer))
// creates a new pointer of a different
// type but the underlying interface value
// knows its "true" type and so cannot be
// meaningfully used through the new pointer.
//
// To make this work, the interpreter needs to
// simulate the memory layout of a real
// compiled implementation.
//
// To at least preserve type-safety, we'll
// just return the zero value of the
// destination type.
return zero(t_dst)
}
// Conversions between complex numeric types?
if ut_src.Info()&types.IsComplex != 0 {
switch ut_dst.(*types.Basic).Kind() {
case types.Complex64:
return complex64(x.(complex128))
case types.Complex128:
return x.(complex128)
}
break // fail: no other conversions for complex
}
// Conversions between non-complex numeric types?
if ut_src.Info()&types.IsNumeric != 0 {
kind := ut_dst.(*types.Basic).Kind()
switch x := x.(type) {
case int64: // signed integer -> numeric?
switch kind {
case types.Int:
return int(x)
case types.Int8:
return int8(x)
case types.Int16:
return int16(x)
case types.Int32:
return int32(x)
case types.Int64:
return int64(x)
case types.Uint:
return uint(x)
case types.Uint8:
return uint8(x)
case types.Uint16:
return uint16(x)
case types.Uint32:
return uint32(x)
case types.Uint64:
return uint64(x)
case types.Uintptr:
return uintptr(x)
case types.Float32:
return float32(x)
case types.Float64:
return float64(x)
}
case uint64: // unsigned integer -> numeric?
switch kind {
case types.Int:
return int(x)
case types.Int8:
return int8(x)
case types.Int16:
return int16(x)
case types.Int32:
return int32(x)
case types.Int64:
return int64(x)
case types.Uint:
return uint(x)
case types.Uint8:
return uint8(x)
case types.Uint16:
return uint16(x)
case types.Uint32:
return uint32(x)
case types.Uint64:
return uint64(x)
case types.Uintptr:
return uintptr(x)
case types.Float32:
return float32(x)
case types.Float64:
return float64(x)
}
case float64: // floating point -> numeric?
switch kind {
case types.Int:
return int(x)
case types.Int8:
return int8(x)
case types.Int16:
return int16(x)
case types.Int32:
return int32(x)
case types.Int64:
return int64(x)
case types.Uint:
return uint(x)
case types.Uint8:
return uint8(x)
case types.Uint16:
return uint16(x)
case types.Uint32:
return uint32(x)
case types.Uint64:
return uint64(x)
case types.Uintptr:
return uintptr(x)
case types.Float32:
return float32(x)
case types.Float64:
return float64(x)
}
}
}
}
panic(fmt.Sprintf("unsupported conversion: %s -> %s, dynamic type %T", t_src, t_dst, x))
}
// checkInterface checks that the method set of x implements the
// interface itype.
// On success it returns "", on failure, an error message.
//
func checkInterface(i *interpreter, itype *types.Interface, x iface) string {
if meth, _ := types.MissingMethod(x.t, itype, true); meth != nil {
return fmt.Sprintf("interface conversion: %v is not %v: missing method %s",
x.t, itype, meth.Name())
}
return "" // ok
}
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