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z_string.go
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/
z_string.go
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/*
* Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package runtime
import (
"unsafe"
"github.com/goplus/llgo/internal/runtime/c"
)
// -----------------------------------------------------------------------------
// String is the runtime representation of a string.
// It cannot be used safely or portably and its representation may
// change in a later release.
//
// Unlike reflect.StringHeader, its Data field is sufficient to guarantee the
// data it references will not be garbage collected.
type String struct {
data unsafe.Pointer
len int
}
// EmptyString returns an empty string.
func EmptyString() String {
return String{nil, 0}
}
// NewString creates a new string.
func NewString(data unsafe.Pointer, len int) String {
return String{data, len}
}
// StringCat concatenates two strings.
func StringCat(a, b String) String {
n := a.len + b.len
dest := AllocU(uintptr(n))
c.Memcpy(dest, a.data, uintptr(a.len))
c.Memcpy(c.Advance(dest, a.len), b.data, uintptr(b.len))
return String{dest, n}
}
// -----------------------------------------------------------------------------
// CStrCopy copies a Go string to a C string buffer and returns it.
func CStrCopy(dest unsafe.Pointer, s String) *int8 {
n := s.len
c.Memcpy(dest, s.data, uintptr(n))
arr := (*[1 << 30]int8)(dest)
arr[n] = 0
return (*int8)(dest)
}
func CStrDup(s String) *int8 {
dest := AllocU(uintptr(s.len + 1))
return CStrCopy(dest, s)
}
func NewStringSlice(base String, i, j int) String {
if i < 0 || j < i || j > base.len {
panic("string slice index out of bounds")
}
if i < base.len {
return String{c.Advance(base.data, i), j - i}
}
return String{nil, 0}
}
// -----------------------------------------------------------------------------