Merge pull request #319 from ichiban/fix-spacing-variable-write-term

fix variable's WriteTerm() when following/followed by a letter-digit operator
ichiban · Jun 13, 2024 · 76ad1bf · 76ad1bf
2 parents d6ea349 + 87f8a85
commit 76ad1bf
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Showing 3 changed files with 18 additions and 3 deletions.
diff --git a/engine/variable.go b/engine/variable.go
@@ -28,11 +28,21 @@ func (v Variable) WriteTerm(w io.Writer, opts *WriteOptions, env *Env) error {
  return x.WriteTerm(w, opts, env)
  }
 
+ ew := errWriter{w: w}
+
+ if letterDigit(opts.left.name) {
+ _, _ = ew.Write([]byte(" "))
+ }
  if a, ok := opts.variableNames[v]; ok {
- return a.WriteTerm(w, opts.withQuoted(false).withLeft(operator{}).withRight(operator{}), env)
+ _ = a.WriteTerm(&ew, opts.withQuoted(false).withLeft(operator{}).withRight(operator{}), env)
+ } else {
+ _, _ = ew.Write([]byte(fmt.Sprintf("_%d", v)))
  }
- _, err := w.Write([]byte(fmt.Sprintf("_%d", v)))
- return err
+ if letterDigit(opts.right.name) {
+ _, _ = ew.Write([]byte(" "))
+ }
+
+ return ew.err
 }
 
 func (v Variable) Compare(t Term, env *Env) int {

diff --git a/engine/variable_test.go b/engine/variable_test.go
@@ -21,6 +21,8 @@ func TestVariable_WriteTerm(t *testing.T) {
  }{
  {title: "unnamed", v: x, output: fmt.Sprintf("_%d", x)},
  {title: "variable_names", v: x, opts: WriteOptions{variableNames: map[Variable]Atom{x: NewAtom("Foo")}}, output: `Foo`},
+ {title: "following a letter-digit operator", v: x, opts: WriteOptions{left: operator{name: NewAtom("is")}}, output: fmt.Sprintf(" _%d", x)},
+ {title: "followed by a letter-digit operator", v: x, opts: WriteOptions{right: operator{name: NewAtom("is")}}, output: fmt.Sprintf("_%d ", x)},
  }
 
  var buf bytes.Buffer

diff --git a/interpreter_test.go b/interpreter_test.go
@@ -308,8 +308,11 @@ func TestNew_variableNames(t *testing.T) {
  {name: "55", query: `S=1+T,N=' /*r*/V',write_term(S,[quoted(true), variable_names([N=T])]).`, output: `1+ /*r*/V`},
  {name: "58", query: `S=1+T,N=(+),write_term(S,[quoted(true), variable_names([N=T])]).`, output: `1++`},
  {name: "59", query: `S=T+1,N=(+),write_term(S,[quoted(true), variable_names([N=T])]).`, output: `++1`},
+ {name: "73", query: `S=(1 is T),N='X',write_term(S,[quoted(true), variable_names([N=T])]).`, output: `1 is X`},
  {name: "69", query: `read_term(T, [singletons(1)]).`, waits: true},
  {name: "70", input: `a.`, query: `\+read_term(T, [singletons(1)]).`},
+ {name: "71", query: `write_term(T,[variable_names(['Bad'=T]),variable_names(['Good'=T])]).`, output: `Good`},
+ {name: "72", query: `read_term(T,[singletons([])]).`, waits: true},
  }
 
  for _, tt := range tests {