| // Copyright 2010 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 runtime |
| |
| // The Error interface identifies a run time error. |
| type Error interface { |
| error |
| |
| // RuntimeError is a no-op function but |
| // serves to distinguish types that are run time |
| // errors from ordinary errors: a type is a |
| // run time error if it has a RuntimeError method. |
| RuntimeError() |
| } |
| |
| // A TypeAssertionError explains a failed type assertion. |
| type TypeAssertionError struct { |
| interfaceString string |
| concreteString string |
| assertedString string |
| missingMethod string // one method needed by Interface, missing from Concrete |
| } |
| |
| func (*TypeAssertionError) RuntimeError() {} |
| |
| func (e *TypeAssertionError) Error() string { |
| inter := e.interfaceString |
| if inter == "" { |
| inter = "interface" |
| } |
| if e.concreteString == "" { |
| return "interface conversion: " + inter + " is nil, not " + e.assertedString |
| } |
| if e.missingMethod == "" { |
| return "interface conversion: " + inter + " is " + e.concreteString + |
| ", not " + e.assertedString |
| } |
| return "interface conversion: " + e.concreteString + " is not " + e.assertedString + |
| ": missing method " + e.missingMethod |
| } |
| |
| // An errorString represents a runtime error described by a single string. |
| type errorString string |
| |
| func (e errorString) RuntimeError() {} |
| |
| func (e errorString) Error() string { |
| return "runtime error: " + string(e) |
| } |
| |
| type stringer interface { |
| String() string |
| } |
| |
| func typestring(x interface{}) string { |
| e := efaceOf(&x) |
| return *e._type._string |
| } |
| |
| // For calling from C. |
| // Prints an argument passed to panic. |
| // There's room for arbitrary complexity here, but we keep it |
| // simple and handle just a few important cases: int, string, and Stringer. |
| func printany(i interface{}) { |
| switch v := i.(type) { |
| case nil: |
| print("nil") |
| case stringer: |
| print(v.String()) |
| case error: |
| print(v.Error()) |
| case int: |
| print(v) |
| case string: |
| print(v) |
| default: |
| print("(", typestring(i), ") ", i) |
| } |
| } |
| |
| // called from generated code |
| func panicwrap(pkg, typ, meth string) { |
| panic("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer") |
| } |