PR #21: Add Map() and FilterFunc()

* Map() exports the properties as a map[string]string.
* FilterFunc() allows filtering through a boolean function.

properties.go

@@ -622,6 +622,30 @@ func (p *Properties) WriteComment(w io.Writer, prefix string, enc Encoding) (n i
 	return
 }
 
+// Map returns a copy of the properties as a map.
+func (p *Properties) Map() map[string]string {
+	m := make(map[string]string)
+	for k, v := range p.m {
+		m[k] = v
+	}
+	return m
+}
+
+// FilterFunc returns a copy of the properties which includes the values which passed all filters.
+func (p *Properties) FilterFunc(filters ...func(k, v string) bool) *Properties {
+	pp := NewProperties()
+outer:
+	for k, v := range p.m {
+		for _, f := range filters {
+			if !f(k, v) {
+				continue outer
+			}
+			pp.Set(k, v)
+		}
+	}
+	return pp
+}
+
 // ----------------------------------------------------------------------------
 
 // Delete removes the key and its comments.

properties_test.go

@@ -826,6 +826,23 @@ func TestMerge(t *testing.T) {
 	assert.Equal(t, p1.GetComment("key"), "another comment")
 }
 
+func TestMap(t *testing.T) {
+	input := "key=value\nabc=def"
+	p := mustParse(t, input)
+	m := map[string]string{"key": "value", "abc": "def"}
+	assert.Equal(t, p.Map(), m)
+}
+
+func TestFilterFunc(t *testing.T) {
+	input := "key=value\nabc=def"
+	p := mustParse(t, input)
+	pp := p.FilterFunc(func(k, v string) bool {
+		return k != "abc"
+	})
+	m := map[string]string{"key": "value"}
+	assert.Equal(t, pp.Map(), m)
+}
+
 // ----------------------------------------------------------------------------
 
 // tests all combinations of delimiters, leading and/or trailing whitespace and newlines.