| // Copyright 2011 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 builtin provides documentation for Go's built-in functions. |
| The functions documented here are not actually in package builtin |
| but their descriptions here allow godoc to present documentation |
| for the language's special functions. |
| */ |
| package builtin |
| |
| // Type is here for the purposes of documentation only. It is a stand-in |
| // for any Go type, but represents the same type for any given function |
| // invocation. |
| type Type int |
| |
| // IntegerType is here for the purposes of documentation only. It is a stand-in |
| // for any integer type: int, uint, int8 etc. |
| type IntegerType int |
| |
| // FloatType is here for the purposes of documentation only. It is a stand-in |
| // for either float type: float32 or float64. |
| type FloatType int |
| |
| // ComplexType is here for the purposes of documentation only. It is a |
| // stand-in for either complex type: complex64 or complex128. |
| type ComplexType int |
| |
| // The append built-in function appends elements to the end of a slice. If |
| // it has sufficient capacity, the destination is resliced to accommodate the |
| // new elements. If it does not, a new underlying array will be allocated. |
| // Append returns the updated slice. It is therefore necessary to store the |
| // result of append, often in the variable holding the slice itself: |
| // slice = append(slice, elem1, elem2) |
| // slice = append(slice, anotherSlice...) |
| func append(slice []Type, elems ...Type) []Type |
| |
| // The copy built-in function copies elements from a source slice into a |
| // destination slice. (As a special case, it also will copy bytes from a |
| // string to a slice of bytes.) The source and destination may overlap. Copy |
| // returns the number of elements copied, which will be the minimum of |
| // len(src) and len(dst). |
| func copy(dst, src []Type) int |
| |
| // The len built-in function returns the length of v, according to its type: |
| // Array: the number of elements in v. |
| // Pointer to array: the number of elements in *v (even if v is nil). |
| // Slice, or map: the number of elements in v; if v is nil, len(v) is zero. |
| // String: the number of bytes in v. |
| // Channel: the number of elements queued (unread) in the channel buffer; |
| // if v is nil, len(v) is zero. |
| func len(v Type) int |
| |
| // The cap built-in function returns the capacity of v, according to its type: |
| // Array: the number of elements in v (same as len(v)). |
| // Pointer to array: the number of elements in *v (same as len(v)). |
| // Slice: the maximum length the slice can reach when resliced; |
| // if v is nil, cap(v) is zero. |
| // Channel: the channel buffer capacity, in units of elements; |
| // if v is nil, cap(v) is zero. |
| func cap(v Type) int |
| |
| // The make built-in function allocates and initializes an object of type |
| // slice, map, or chan (only). Like new, the first argument is a type, not a |
| // value. Unlike new, make's return type is the same as the type of its |
| // argument, not a pointer to it. The specification of the result depends on |
| // the type: |
| // Slice: The size specifies the length. The capacity of the slice is |
| // equal to its length. A second integer argument may be provided to |
| // specify a different capacity; it must be no smaller than the |
| // length, so make([]int, 0, 10) allocates a slice of length 0 and |
| // capacity 10. |
| // Map: An initial allocation is made according to the size but the |
| // resulting map has length 0. The size may be omitted, in which case |
| // a small starting size is allocated. |
| // Channel: The channel's buffer is initialized with the specified |
| // buffer capacity. If zero, or the size is omitted, the channel is |
| // unbuffered. |
| func make(Type, size IntegerType) Type |
| |
| // The new built-in function allocates memory. The first argument is a type, |
| // not a value, and the value returned is a pointer to a newly |
| // allocated zero value of that type. |
| func new(Type) *Type |
| |
| // The complex built-in function constructs a complex value from two |
| // floating-point values. The real and imaginary parts must be of the same |
| // size, either float32 or float64 (or assignable to them), and the return |
| // value will be the corresponding complex type (complex64 for float32, |
| // complex128 for float64). |
| func complex(r, i FloatType) ComplexType |
| |
| // The real built-in function returns the real part of the complex number c. |
| // The return value will be floating point type corresponding to the type of c. |
| func real(c ComplexType) FloatType |
| |
| // The imaginary built-in function returns the imaginary part of the complex |
| // number c. The return value will be floating point type corresponding to |
| // the type of c. |
| func imag(c ComplexType) FloatType |
| |
| // The close built-in function closes a channel, which must be either |
| // bidirectional or send-only. It should be executed only by the sender, |
| // never the receiver, and has the effect of shutting down the channel after |
| // the last sent value is received. After the last value has been received |
| // from a closed channel c, any receive from c will succeed without |
| // blocking, returning the zero value for the channel element. The form |
| // x, ok := <-c |
| // will also set ok to false for a closed channel. |
| func close(c chan<- Type) |
| |
| // The panic built-in function stops normal execution of the current |
| // goroutine. When a function F calls panic, normal execution of F stops |
| // immediately. Any functions whose execution was deferred by F are run in |
| // the usual way, and then F returns to its caller. To the caller G, the |
| // invocation of F then behaves like a call to panic, terminating G's |
| // execution and running any deferred functions. This continues until all |
| // functions in the executing goroutine have stopped, in reverse order. At |
| // that point, the program is terminated and the error condition is reported, |
| // including the value of the argument to panic. This termination sequence |
| // is called panicking and can be controlled by the built-in function |
| // recover. |
| func panic(v interface{}) |
| |
| // The recover built-in function allows a program to manage behavior of a |
| // panicking goroutine. Executing a call to recover inside a deferred |
| // function (but not any function called by it) stops the panicking sequence |
| // by restoring normal execution and retrieves the error value passed to the |
| // call of panic. If recover is called outside the deferred function it will |
| // not stop a panicking sequence. In this case, or when the goroutine is not |
| // panicking, or if the argument supplied to panic was nil, recover returns |
| // nil. Thus the return value from recover reports whether the goroutine is |
| // panicking. |
| func recover() interface{} |