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|
// Package dump contains some helper functions for printing and formatting
// values.
package dump
import (
"bytes"
"fmt"
"go/scanner"
"go/token"
"strings"
)
// Value produces a formatted string representation of the given value.
//
// The result is a pretty-printed version of the result of the fmt.GoStringer
// implementation for the given value. The pretty-printing expects the
// GoString result to be a valid Go expression; if it is not then the result
// may be sub-optimal but this function will still make a best effort.
//
// This function is intended primarily as a helper for writing unit tests, and
// so it is not optimized for performance in any way.
func Value(v interface{}) string {
return prettyPrint(fmt.Sprintf("%#v", v))
}
func prettyPrint(s string) string {
var buf bytes.Buffer
fs := token.NewFileSet()
f := fs.AddFile("", -1, len(s))
sc := &scanner.Scanner{}
sc.Init(f, []byte(s), nil, scanner.ScanComments)
type Token struct {
Type token.Token
Str string
}
var tokens []Token
for {
_, tok, lit := sc.Scan()
switch tok {
case token.IDENT, token.INT, token.FLOAT, token.IMAG, token.CHAR, token.STRING, token.COMMENT, token.SEMICOLON, token.ILLEGAL:
// "lit" is already populated
default:
lit = tok.String()
}
tokens = append(tokens, Token{
Type: tok,
Str: lit,
})
if tok == token.EOF {
break
}
}
indent := 0
otherBrackets := 0
emptyBraces := false
for i, tok := range tokens {
if tok.Type == token.EOF {
break
}
nextTok := tokens[i+1]
switch {
case tok.Type == token.LBRACE:
if otherBrackets > 0 {
buf.WriteString("{")
continue
}
if nextTok.Type == token.RBRACE {
buf.WriteString("{")
emptyBraces = true
continue
}
indent++
buf.WriteString("{\n" + strings.Repeat(" ", indent))
case tok.Type == token.RBRACE:
if otherBrackets > 0 {
buf.WriteString("}")
continue
}
if emptyBraces {
buf.WriteString("}")
emptyBraces = false
continue
}
indent--
sp := strings.Repeat(" ", indent)
if nextTok.Type == token.SEMICOLON || nextTok.Type == token.COMMA || nextTok.Type == token.RBRACE {
buf.WriteString(fmt.Sprintf("\n%s}", sp))
} else {
buf.WriteString(fmt.Sprintf("\n%s}\n%s", sp, sp))
}
case tok.Type == token.LBRACK || tok.Type == token.LPAREN:
buf.WriteString(tok.Str)
otherBrackets++
case tok.Type == token.RBRACK || tok.Type == token.RPAREN:
buf.WriteString(tok.Str)
otherBrackets--
case tok.Type == token.COMMA:
if otherBrackets > 0 {
buf.WriteString(", ")
continue
}
buf.WriteString(",\n" + strings.Repeat(" ", indent))
case tok.Type == token.SEMICOLON:
if otherBrackets > 0 {
buf.WriteString("; ")
continue
}
buf.WriteString("\n" + strings.Repeat(" ", indent))
case tok.Type == token.COLON:
buf.WriteString(": ")
default:
buf.WriteString(tok.Str)
}
}
return buf.String()
}
|
