diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go index 7a4ad7d00bb..6bb3e388eb5 100644 --- a/src/pkg/fmt/fmt_test.go +++ b/src/pkg/fmt/fmt_test.go @@ -78,6 +78,23 @@ type C struct { B } +type F int + +func (f F) Format(s State, c int) { + Fprintf(s, "<%c=F(%d)>", c, int(f)) +} + +type G int + +func (g G) GoString() string { + return Sprintf("GoString(%d)", int(g)) +} + +type S struct { + f F // a struct field that Formats + g G // a struct field that GoStrings +} + var b byte var fmttests = []fmtTest{ @@ -322,6 +339,15 @@ var fmttests = []fmtTest{ fmtTest{"%v", renamedComplex64(3 + 4i), "(3+4i)"}, fmtTest{"%v", renamedComplex128(4 - 3i), "(4-3i)"}, + // Formatter + fmtTest{"%x", F(1), ""}, + fmtTest{"%x", G(2), "2"}, + fmtTest{"%+v", S{F(4), G(5)}, "{f: g:5}"}, + + // GoStringer + fmtTest{"%#v", G(6), "GoString(6)"}, + fmtTest{"%#v", S{F(7), G(8)}, "fmt_test.S{f:, g:GoString(8)}"}, + // %T fmtTest{"%T", (4 - 3i), "complex"}, fmtTest{"%T", renamedComplex128(4 - 3i), "fmt_test.renamedComplex128"}, @@ -546,3 +572,22 @@ func TestBlankln(t *testing.T) { t.Errorf("got %q expected %q", got, expect) } } + + +// Check Formatter with Sprint, Sprintln, Sprintf +func TestFormatterPrintln(t *testing.T) { + f := F(1) + expect := "\n" + s := Sprint(f, "\n") + if s != expect { + t.Errorf("Sprint wrong with Formatter: expected %q got %q\n", expect, s) + } + s = Sprintln(f) + if s != expect { + t.Errorf("Sprintln wrong with Formatter: expected %q got %q\n", expect, s) + } + s = Sprintf("%v\n", f) + if s != expect { + t.Errorf("Sprintf wrong with Formatter: expected %q got %q\n", expect, s) + } +} diff --git a/src/pkg/fmt/print.go b/src/pkg/fmt/print.go index d1ceb7c35fb..302c02f59f5 100644 --- a/src/pkg/fmt/print.go +++ b/src/pkg/fmt/print.go @@ -493,18 +493,44 @@ var ( ) func (p *pp) printField(field interface{}, verb int, plus, goSyntax bool, depth int) (wasString bool) { - if field != nil { - switch { - default: - if stringer, ok := field.(Stringer); ok { - p.printField(stringer.String(), verb, plus, goSyntax, depth) - return false // this value is not a string - } - case goSyntax: - if stringer, ok := field.(GoStringer); ok { - p.printField(stringer.GoString(), verb, plus, goSyntax, depth) - return false // this value is not a string - } + if field == nil { + if verb == 'T' || verb == 'v' { + p.buf.Write(nilAngleBytes) + } else { + p.badVerb(verb, field) + } + return false + } + + // Special processing considerations. + // %T (the value's type) is special; we always do it first. + if verb == 'T' { + p.printField(reflect.Typeof(field).String(), 's', false, false, 0) + return false + } + // Is it a Formatter? + if formatter, ok := field.(Formatter); ok { + formatter.Format(p, verb) + return false // this value is not a string + + } + // Must not touch flags before Formatter looks at them. + if plus { + p.fmt.plus = false + } + // If we're doing Go syntax and the field knows how to supply it, take care of it now. + if goSyntax { + p.fmt.sharp = false + if stringer, ok := field.(GoStringer); ok { + // Print the result of GoString unadorned. + p.fmtString(stringer.GoString(), 's', false, field) + return false // this value is not a string + } + } else { + // Is it a Stringer? + if stringer, ok := field.(Stringer); ok { + p.printField(stringer.String(), verb, plus, false, depth) + return false // this value is not a string } } @@ -580,15 +606,6 @@ func (p *pp) printField(field interface{}, verb int, plus, goSyntax bool, depth return verb == 's' } - if field == nil { - if verb == 'v' { - p.buf.Write(nilAngleBytes) - } else { - p.badVerb(verb, field) - } - return false - } - value := reflect.NewValue(field) // Need to use reflection // Special case for reflection values that know how to print with %p. @@ -802,33 +819,8 @@ func (p *pp) doPrintf(format string, a []interface{}) { field := a[fieldnum] fieldnum++ - // %T is special; we always do it here. - if c == 'T' { - // the value's type - if field == nil { - p.buf.Write(nilAngleBytes) - break - } - p.printField(reflect.Typeof(field).String(), 's', false, false, 0) - continue - } - - // Try Formatter (except for %T). - if field != nil { - if formatter, ok := field.(Formatter); ok { - formatter.Format(p, c) - continue - } - } - goSyntax := c == 'v' && p.fmt.sharp - if goSyntax { - p.fmt.sharp = false - } plus := c == 'v' && p.fmt.plus - if plus { - p.fmt.plus = false - } p.printField(field, c, plus, goSyntax, 0) }