github.com/go-xe2/third@v1.0.3/golang.org/x/text/internal/triegen/example_compact_test.go (about)

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package triegen_test
     6  
     7  import (
     8  	"fmt"
     9  	"io"
    10  	"io/ioutil"
    11  
    12  	"github.com/go-xe2/third/golang.org/x/text/internal/triegen"
    13  )
    14  
    15  func ExampleCompacter() {
    16  	t := triegen.NewTrie("root")
    17  	for r := rune(0); r < 10000; r += 64 {
    18  		t.Insert(r, 0x9015BADA55^uint64(r))
    19  	}
    20  	sz, _ := t.Gen(ioutil.Discard)
    21  
    22  	fmt.Printf("Size normal:    %5d\n", sz)
    23  
    24  	var c myCompacter
    25  	sz, _ = t.Gen(ioutil.Discard, triegen.Compact(&c))
    26  
    27  	fmt.Printf("Size compacted: %5d\n", sz)
    28  
    29  	// Output:
    30  	// Size normal:    81344
    31  	// Size compacted:  3224
    32  }
    33  
    34  // A myCompacter accepts a block if only the first value is given.
    35  type myCompacter []uint64
    36  
    37  func (c *myCompacter) Size(values []uint64) (sz int, ok bool) {
    38  	for _, v := range values[1:] {
    39  		if v != 0 {
    40  			return 0, false
    41  		}
    42  	}
    43  	return 8, true // the size of a uint64
    44  }
    45  
    46  func (c *myCompacter) Store(v []uint64) uint32 {
    47  	x := uint32(len(*c))
    48  	*c = append(*c, v[0])
    49  	return x
    50  }
    51  
    52  func (c *myCompacter) Print(w io.Writer) error {
    53  	fmt.Fprintln(w, "var firstValue = []uint64{")
    54  	for _, v := range *c {
    55  		fmt.Fprintf(w, "\t%#x,\n", v)
    56  	}
    57  	fmt.Fprintln(w, "}")
    58  	return nil
    59  }
    60  
    61  func (c *myCompacter) Handler() string {
    62  	return "getFirstValue"
    63  
    64  	// Where getFirstValue is included along with the generated code:
    65  	// func getFirstValue(n uint32, b byte) uint64 {
    66  	//     if b == 0x80 { // the first continuation byte
    67  	//         return firstValue[n]
    68  	//     }
    69  	//     return 0
    70  	//  }
    71  }