github.com/creachadair/ffs@v0.17.3/block/example_test.go (about)

     1  // Copyright 2019 Michael J. Fromberger. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package block_test
    16  
    17  import (
    18  	"fmt"
    19  	"log"
    20  	"strings"
    21  
    22  	"github.com/creachadair/ffs/block"
    23  )
    24  
    25  func Example() {
    26  	// Note that these two strings are similar, but the second one has been
    27  	// edited. The edit changes the block splits around the point of the edit,
    28  	// but the sliding window allows them to resynchronize after the break.
    29  	const input1 = `abcdefg-hijklmnop-qrstuv-wxyz-abcdefg-hijklmnop-qrstuv-wxyz-abcdefghijklmnopqrstuv`
    30  	const input2 = `abcdefg-hijklmnop-qrstuv-wxyz-*-abcdefg-hijklmnop-qrstuv-wxyz-abcdefghijklmnopqrstuv`
    31  
    32  	opts := &block.SplitConfig{
    33  		Min:    5,  // no blocks shorter than this
    34  		Size:   10, // desired mean block size
    35  		Max:    20, // no blocks longer than this
    36  		Hasher: block.RabinKarpHasher(23, 997, 13),
    37  	}
    38  
    39  	for _, v := range []string{input1, input2} {
    40  		s := block.NewSplitter(strings.NewReader(v), opts)
    41  		var i int
    42  		if err := s.Split(func(data []byte) error {
    43  			i++
    44  			fmt.Printf("%d. %s\n", i, string(data))
    45  			return nil
    46  		}); err != nil {
    47  			log.Fatal(err)
    48  		}
    49  		fmt.Println()
    50  	}
    51  
    52  	// Output:
    53  	//
    54  	// 1. abcdefg-h
    55  	// 2. ijklmnop-qrstu
    56  	// 3. v-wxyz-abcdefg
    57  	// 4. -hijklmnop-qrstu
    58  	// 5. v-wxyz-abcdefghijklm
    59  	// 6. nopqrstuv
    60  	//
    61  	// 1. abcdefg-h
    62  	// 2. ijklmnop-qrstu
    63  	// 3. v-wxyz-*-
    64  	// 4. abcdefg-hi
    65  	// 5. jklmnop-qrstu
    66  	// 6. v-wxyz-abcdefghijklm
    67  	// 7. nopqrstuv
    68  }