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