141 lines
3.6 KiB
Go
141 lines
3.6 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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// The Error interface identifies a run time error.
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type Error interface {
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error
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// RuntimeError is a no-op function but
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// serves to distinguish types that are runtime
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// errors from ordinary errors: a type is a
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// runtime error if it has a RuntimeError method.
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RuntimeError()
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}
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// A TypeAssertionError explains a failed type assertion.
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type TypeAssertionError struct {
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interfaceType *Type // interface had this type
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concreteType *Type // concrete value had this type
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assertedType *Type // asserted type
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interfaceString string
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concreteString string
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assertedString string
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missingMethod string // one method needed by Interface, missing from Concrete
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}
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func (*TypeAssertionError) RuntimeError() {}
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func (e *TypeAssertionError) Error() string {
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inter := e.interfaceString
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if inter == "" {
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inter = "interface"
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}
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if e.concreteType == nil {
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return "interface conversion: " + inter + " is nil, not " + e.assertedString
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}
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if e.missingMethod == "" {
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return "interface conversion: " + inter + " is " + e.concreteString +
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", not " + e.assertedString
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}
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return "interface conversion: " + e.concreteString + " is not " + e.assertedString +
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": missing method " + e.missingMethod
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}
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// Concrete returns the type of the concrete value in the failed type assertion.
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// If the interface value was nil, Concrete returns nil.
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func (e *TypeAssertionError) Concrete() *Type {
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return e.concreteType
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}
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// Asserted returns the type incorrectly asserted by the type assertion.
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func (e *TypeAssertionError) Asserted() *Type {
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return e.assertedType
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}
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// If the type assertion is to an interface type, MissingMethod returns the
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// name of a method needed to satisfy that interface type but not implemented
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// by Concrete. If there are multiple such methods,
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// MissingMethod returns one; which one is unspecified.
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// If the type assertion is not to an interface type, MissingMethod returns an empty string.
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func (e *TypeAssertionError) MissingMethod() string {
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return e.missingMethod
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}
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// For calling from C.
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func NewTypeAssertionError(pt1, pt2, pt3 *Type, ps1, ps2, ps3 *string, pmeth *string, ret *interface{}) {
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var t1, t2, t3 *Type
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var s1, s2, s3, meth string
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if pt1 != nil {
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t1 = pt1
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}
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if pt2 != nil {
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t2 = pt2
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}
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if pt3 != nil {
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t3 = pt3
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}
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if ps1 != nil {
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s1 = *ps1
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}
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if ps2 != nil {
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s2 = *ps2
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}
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if ps3 != nil {
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s3 = *ps3
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}
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if pmeth != nil {
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meth = *pmeth
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}
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*ret = &TypeAssertionError{t1, t2, t3, s1, s2, s3, meth}
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}
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// An errorString represents a runtime error described by a single string.
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type errorString string
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func (e errorString) RuntimeError() {}
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func (e errorString) Error() string {
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return "runtime error: " + string(e)
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}
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// For calling from C.
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func NewErrorString(s string, ret *interface{}) {
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*ret = errorString(s)
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}
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type stringer interface {
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String() string
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}
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func typestring(interface{}) string
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// For calling from C.
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// Prints an argument passed to panic.
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// There's room for arbitrary complexity here, but we keep it
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// simple and handle just a few important cases: int, string, and Stringer.
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func Printany(i interface{}) {
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switch v := i.(type) {
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case nil:
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print("nil")
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case stringer:
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print(v.String())
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case error:
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print(v.Error())
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case int:
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print(v)
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case string:
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print(v)
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default:
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print("(", typestring(i), ") ", i)
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}
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}
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// called from generated code
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func panicwrap(pkg, typ, meth string) {
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panic("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer")
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}
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