映えるGoコード

CSSで柔軟にカスタマイズできるコードハイライトツールの紹介

Dennis Metzger
golang.tokyo #42

Dennis(デニス) Metzger(メッツガー)

Backend Engineer @ Finatext

					
						package main

						import "fmt"

						func main() {
							ch := make(chan float64)
							ch <- 1.0e10 // magic number
							x, ok := <-ch
							defer fmt.Println(`exiting now`)
							go println(len("hello world!"))
							return
						}
					
					
					
						package main

						import "fmt"

						func main() {
							ch := make(chan float64)
							ch <- 1.0e10 // magic number
							x, ok := <-ch
							defer fmt.Println(`exiting now`)
							go println(len("hello world!"))
							return
						}
					
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
					
						<pre>
							<code class="language-go">
								package main

								import "fmt"

								func main() {
									ch := make(chan float64)
									ch <- 1.0e10 // magic number
									x, ok := <-ch
									defer fmt.Println(`exiting now`)
									go println(len("hello world!"))
									return
								}
							</code>
						</pre>
					
					
					
						
  1. package main
    2. 
						
  2. 
						
  3. import "fmt"
    4. 
						
  4. 
						
  5. func main() {
    6. 
						
  6. 	ch := make(chan float64)
    7. 
						
  7. 	ch <- 1.0e10 // magic number
    8. 
						
  8. 	x, ok := <-ch
    9. 
						
  9. 	defer fmt.Println(`exiting now`)
    10. 
						
  10. 	go println(len("hello world!"))
    11. 
						
  11. 	return
    12. 
						
  12. }
    13. 
						

					
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13. 
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	ch := make(chan float64)
    7. 
					
  7. 	ch <- 1.0e10 // magic number
    8. 
					
  8. 	x, ok := <-ch
    9. 
					
  9. 	defer fmt.Println(`exiting now`)
    10. 
					
  10. 	go println(len("hello world!"))
    11. 
					
  11. 	return
    12. 
					
  12. }
    13.

完成までの道のり

❯ gopls semtok ./main.go 
    
					
  1. package main
    2. 
					
  2. 
					
  3. import "fmt"
    4. 
					
  4. 
					
  5. func main() {
    6. 
					
  6. 	fmt.Println("Hello, World!")
    7. 
					
  7. }
    8. 
					
    
					
  1. /*⇒7,keyword,[]*/package /*⇒4,namespace,[]*/main
    2. 
					
  2. 
					
  3. /*⇒6,keyword,[]*/import "fmt"/*⇐3,namespace,[]*/
    4. 
					
  4. 
					
  5. /*⇒4,keyword,[]*/func /*⇒4,function,[definition signature]*/main() {
    6. 
					
  6.         /*⇒3,namespace,[]*/fmt./*⇒7,function,[signature]*/Println(/*⇒15,string,[]*/"Hello, World!")
    7. 
					
  7. }
    8.
/*⇒4,function,[definition signature]*/main
github.com/golang/tools
/gopls/internal/golang/semtok.go
github.com/golang/tools
/gopls/internal/golang/semtok.go
必要なコードを切り出し、
実行してみると……
❯ echo a := 1 > test.go

❯ go run ./cmd/prettygo ./test.go


ん？
❯ gopls semtok ./test.go


ん？？

go/parser/parser.go から

 
func (p *parser) parseFile() *ast.File {
	// 中略

	// Don't bother parsing the rest if we
	// had errors scanning the first token.
	// Likely not a Go source file at all.
	if p.errors.Len() != 0 {
		return nil
	}

go/parser/parser.go から

 
	// 中略
	pos := p.expect(token.PACKAGE)
	// 中略

	// Don't bother parsing the rest if we 
	// had errors parsing the package clause.
	// Likely not a Go source file at all.
	if p.errors.Len() != 0 {
		return nil
	}

go/parser/parser.go から

 
func (p *parser) expect(/*中略*/) token.Pos {
	pos := p.pos
	if p.tok != tok {
		p.errorExpected(/*中略*/)
	} else {
		p.firstTokenFound = true
	}
	if p.firstTokenFound {
		p.next() // make progress
	}
	return pos
}

go/parser/parser.go から

 
  1. func (p *parser) expect(/*中略*/) token.Pos {
    2. 
						
  2. 	pos := p.pos
    3. 
						
  3. 	if p.tok != tok {
    4. 
						
  4. 		p.errorExpected(/*中略*/)
    5. 
						
  5. 	} else {
    6. 
						
  6. 		p.firstTokenFound = true
    7. 
						
  7. 	}
    8. 
						
  8. 	if p.firstTokenFound {
    9. 
						
  9. 		p.next() // make progress
    10. 
						
  10. 	}
    11. 
						
  11. 	return pos
    12. 
						
  12. }

AST に足りない要素を追加






a := 1 

    
								
  1. package main
    2. 
								
  2. 
								
  3. func init() {}
    4. 
								
  4. 
								
  5. func main() {
    6. 
								
  6. 	a := 1
    7. 
								
  7. }
    8.
良い感じにできたと思ったら⋯⋯

🚨バグ発見🚨

    
						
  1. str := `
    2. 
						
    3. 
						
    4. 
						
    5. 
						
    6. 
						
  6. test`
    7. 
					
    
						
  1. str := `\r\n
    2. 
						
  2. \r\n
    3. 
						
  3. \r\n
    4. 
						
  4. \r\n
    5. 
						
  5. \r\n
    6. 
						
  6. test`
    7. 
					
    
						
  1. str := /*⇒1,string,[]*/`
    2. 
						
  2. /*⇒0,string,[]*/
    3. 
						
  3. /*⇒0,string,[]*/
    4. 
						
  4. /*⇒0,string,[]*/
    5. 
						
  5. /*⇒1,string,[]*/test`
    6.
https://github.com/golang/go/issues/75969

で報告し、対応済み

完成

以上、prettygo の仕組みでした！

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ご活用ください

PRもお待ちしています！

https://github.com/sollniss/prettygo