go/types: return typeHash value without blanks

This is an adjusted port of CL 349990 from types2 to go/types:
typeHash remains unexported but is adjusted to not contain blanks.

Change-Id: I37fa826b8a185e3c275ae9bea29a3b0ed386d2c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/351171
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

diff --git a/src/go/types/environment.go b/src/go/types/environment.go
index 61fc3c5348b236677b09bbe3121ee0371856cfa3..b818f8156463b8c9cbf6a67c8a8fdc7b860aaa35 100644 (file)
--- a/src/go/types/environment.go
+++ b/src/go/types/environment.go
@@ -6,6 +6,7 @@ package types
 
 import (
        "bytes"
+       "strings"
        "sync"
 )
 
@@ -32,7 +33,7 @@ func NewEnvironment() *Environment {
 // typeHash returns a string representation of typ, which can be used as an exact
 // type hash: types that are identical produce identical string representations.
 // If typ is a *Named type and targs is not empty, typ is printed as if it were
-// instantiated with targs.
+// instantiated with targs. The result is guaranteed to not contain blanks (" ").
 func (env *Environment) typeHash(typ Type, targs []Type) string {
        assert(env != nil)
        assert(typ != nil)
@@ -50,7 +51,7 @@ func (env *Environment) typeHash(typ Type, targs []Type) string {
                h.typ(typ)
        }
 
-       return buf.String()
+       return strings.Replace(buf.String(), " ", "#", -1) // ReplaceAll is not available in Go1.4
 }
 
 // typeForHash returns the recorded type for the type hash h, if it exists.

diff --git a/src/go/types/typestring.go b/src/go/types/typestring.go
index eadc50a7549684e803209faf2d672e655abfe343..e5dafc2e0d8f535e585065eda901d9f5dfc5ce21 100644 (file)
--- a/src/go/types/typestring.go
+++ b/src/go/types/typestring.go
@@ -8,7 +8,6 @@ package types
 
 import (
        "bytes"
-       "fmt"
        "go/token"
        "strconv"
        "unicode/utf8"
@@ -81,14 +80,29 @@ func newTypeHasher(buf *bytes.Buffer, env *Environment) *typeWriter {
        return &typeWriter{buf, make(map[Type]bool), nil, env}
 }
 
-func (w *typeWriter) byte(b byte)                               { w.buf.WriteByte(b) }
-func (w *typeWriter) string(s string)                           { w.buf.WriteString(s) }
-func (w *typeWriter) writef(format string, args ...interface{}) { fmt.Fprintf(w.buf, format, args...) }
+func (w *typeWriter) byte(b byte) {
+       if w.env != nil {
+               if b == ' ' {
+                       b = '#'
+               }
+               w.buf.WriteByte(b)
+               return
+       }
+       w.buf.WriteByte(b)
+       if b == ',' || b == ';' {
+               w.buf.WriteByte(' ')
+       }
+}
+
+func (w *typeWriter) string(s string) {
+       w.buf.WriteString(s)
+}
+
 func (w *typeWriter) error(msg string) {
        if w.env != nil {
                panic(msg)
        }
-       w.string("<" + msg + ">")
+       w.buf.WriteString("<" + msg + ">")
 }
 
 func (w *typeWriter) typ(typ Type) {
@@ -115,7 +129,9 @@ func (w *typeWriter) typ(typ Type) {
                w.string(t.name)
 
        case *Array:
-               w.writef("[%d]", t.len)
+               w.byte('[')
+               w.string(strconv.FormatInt(t.len, 10))
+               w.byte(']')
                w.typ(t.elem)
 
        case *Slice:
@@ -126,7 +142,7 @@ func (w *typeWriter) typ(typ Type) {
                w.string("struct{")
                for i, f := range t.fields {
                        if i > 0 {
-                               w.string("; ")
+                               w.byte(';')
                        }
                        // This doesn't do the right thing for embedded type
                        // aliases where we should print the alias name, not
@@ -137,7 +153,11 @@ func (w *typeWriter) typ(typ Type) {
                        }
                        w.typ(f.typ)
                        if tag := t.Tag(i); tag != "" {
-                               w.writef(" %q", tag)
+                               w.byte(' ')
+                               // TODO(rfindley) If tag contains blanks, replacing them with '#'
+                               //                in Environment.TypeHash may produce another tag
+                               //                accidentally.
+                               w.string(strconv.Quote(tag))
                        }
                }
                w.byte('}')
@@ -175,7 +195,7 @@ func (w *typeWriter) typ(typ Type) {
                first := true
                for _, m := range t.methods {
                        if !first {
-                               w.string("; ")
+                               w.byte(';')
                        }
                        first = false
                        w.string(m.name)
@@ -183,7 +203,7 @@ func (w *typeWriter) typ(typ Type) {
                }
                for _, typ := range t.embeddeds {
                        if !first {
-                               w.string("; ")
+                               w.byte(';')
                        }
                        first = false
                        w.typ(typ)
@@ -270,7 +290,7 @@ func (w *typeWriter) typeList(list []Type) {
        w.byte('[')
        for i, typ := range list {
                if i > 0 {
-                       w.string(", ")
+                       w.byte(',')
                }
                w.typ(typ)
        }
@@ -294,7 +314,7 @@ func (w *typeWriter) tParamList(list []*TypeParam) {
                                w.byte(' ')
                                w.typ(prev)
                        }
-                       w.string(", ")
+                       w.byte(',')
                }
                prev = tpar.bound
                w.typ(tpar)
@@ -318,7 +338,7 @@ func (w *typeWriter) tuple(tup *Tuple, variadic bool) {
        if tup != nil {
                for i, v := range tup.vars {
                        if i > 0 {
-                               w.string(", ")
+                               w.byte(',')
                        }
                        // parameter names are ignored for type identity and thus type hashes
                        if w.env == nil && v.name != "" {