text: // Copyright 2013 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.
  
  // +build ignore
  
  package main
  
  // This program generates tables.go:
  //	go run maketables.go | gofmt > tables.go
  
  import (
  	"bufio"
  	"fmt"
  	"log"
  	"net/http"
  	"sort"
  	"strings"
  )
  
  func main() {
  	fmt.Printf("// generated by go run maketables.go; DO NOT EDIT\n\n")
  	fmt.Printf("// Package korean provides Korean encodings such as EUC-KR.\n")
  	fmt.Printf(`package korean // import "golang.org/x/text/encoding/korean"` + "\n\n")
  
  	res, err := http.Get("http://encoding.spec.whatwg.org/index-euc-kr.txt")
  	if err != nil {
  		log.Fatalf("Get: %v", err)
  	}
  	defer res.Body.Close()
  
  	mapping := [65536]uint16{}
  	reverse := [65536]uint16{}
  
  	scanner := bufio.NewScanner(res.Body)
  	for scanner.Scan() {
  		s := strings.TrimSpace(scanner.Text())
  		if s == "" || s[0] == '#' {
  			continue
  		}
  		x, y := uint16(0), uint16(0)
  		if _, err := fmt.Sscanf(s, "%d 0x%x", &x, &y); err != nil {
  			log.Fatalf("could not parse %q", s)
  		}
  		if x < 0 || 178*(0xc7-0x81)+(0xfe-0xc7)*94+(0xff-0xa1) <= x {
  			log.Fatalf("EUC-KR code %d is out of range", x)
  		}
  		mapping[x] = y
  		if reverse[y] == 0 {
  			c0, c1 := uint16(0), uint16(0)
  			if x < 178*(0xc7-0x81) {
  				c0 = uint16(x/178) + 0x81
  				c1 = uint16(x % 178)
  				switch {
  				case c1 < 1*26:
  					c1 += 0x41
  				case c1 < 2*26:
  					c1 += 0x47
  				default:
  					c1 += 0x4d
  				}
  			} else {
  				x -= 178 * (0xc7 - 0x81)
  				c0 = uint16(x/94) + 0xc7
  				c1 = uint16(x%94) + 0xa1
  			}
  			reverse[y] = c0<<8 | c1
  		}
  	}
  	if err := scanner.Err(); err != nil {
  		log.Fatalf("scanner error: %v", err)
  	}
  
  	fmt.Printf("// decode is the decoding table from EUC-KR code to Unicode.\n")
  	fmt.Printf("// It is defined at http://encoding.spec.whatwg.org/index-euc-kr.txt\n")
  	fmt.Printf("var decode = [...]uint16{\n")
  	for i, v := range mapping {
  		if v != 0 {
  			fmt.Printf("\t%d: 0x%04X,\n", i, v)
  		}
  	}
  	fmt.Printf("}\n\n")
  
  	// Any run of at least separation continuous zero entries in the reverse map will
  	// be a separate encode table.
  	const separation = 1024
  
  	intervals := []interval(nil)
  	low, high := -1, -1
  	for i, v := range reverse {
  		if v == 0 {
  			continue
  		}
  		if low < 0 {
  			low = i
  		} else if i-high >= separation {
  			if high >= 0 {
  				intervals = append(intervals, interval{low, high})
  			}
  			low = i
  		}
  		high = i + 1
  	}
  	if high >= 0 {
  		intervals = append(intervals, interval{low, high})
  	}
  	sort.Sort(byDecreasingLength(intervals))
  
  	fmt.Printf("const numEncodeTables = %d\n\n", len(intervals))
  	fmt.Printf("// encodeX are the encoding tables from Unicode to EUC-KR code,\n")
  	fmt.Printf("// sorted by decreasing length.\n")
  	for i, v := range intervals {
  		fmt.Printf("// encode%d: %5d entries for runes in [%5d, %5d).\n", i, v.len(), v.low, v.high)
  	}
  	fmt.Printf("\n")
  
  	for i, v := range intervals {
  		fmt.Printf("const encode%dLow, encode%dHigh = %d, %d\n\n", i, i, v.low, v.high)
  		fmt.Printf("var encode%d = [...]uint16{\n", i)
  		for j := v.low; j < v.high; j++ {
  			x := reverse[j]
  			if x == 0 {
  				continue
  			}
  			fmt.Printf("\t%d-%d: 0x%04X,\n", j, v.low, x)
  		}
  		fmt.Printf("}\n\n")
  	}
  }
  
  // interval is a half-open interval [low, high).
  type interval struct {
  	low, high int
  }
  
  func (i interval) len() int { return i.high - i.low }
  
  // byDecreasingLength sorts intervals by decreasing length.
  type byDecreasingLength []interval
  
  func (b byDecreasingLength) Len() int           { return len(b) }
  func (b byDecreasingLength) Less(i, j int) bool { return b[i].len() > b[j].len() }
  func (b byDecreasingLength) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
  