Define TypedValue comparators; Make parser init more flexible

pkg/codegen/assets/expr_types.gen.go.tpl

@@ -75,6 +75,33 @@ func (t *{{ $exprType }}) Assign(val interface{}) (error) {
 	}
 }
 
+{{ if $def.Comparable }}
+{{ if not $def.CustomComparator }}
+// Compare the two {{ $exprType }} values
+func (t {{ $exprType }}) Compare(to TypedValue) (int, error) {
+	c, err := New{{ $exprType }}(to)
+	if err != nil {
+		return 0, fmt.Errorf("cannot compare %s and %s: %s", t.Type(), c.Type(), err.Error())
+	}
+
+	switch {
+	case t.value == c.value:
+		return 0, nil
+	case t.value < c.value:
+		return -1, nil
+	case t.value > c.value:
+		return 1, nil
+	default:
+		return 0, fmt.Errorf("cannot compare %s and %s: unknown state", t.Type(), c.Type())
+	}
+}
+{{ else }}
+// Compare the two {{ $exprType }} values
+func (t {{ $exprType }}) Compare(to TypedValue) (int, error) {
+	return compareTo{{ $exprType }}(t, to)
+}
+{{ end }}
+{{ end }}
 
 {{ if $def.Struct }}
 {{ if not $def.CustomFieldAssigner }}

pkg/codegen/expr_types.go

@@ -2,10 +2,11 @@ package codegen
 
 import (
 	"fmt"
-	"gopkg.in/yaml.v3"
 	"os"
 	"path"
 	"text/template"
+
+	"gopkg.in/yaml.v3"
 )
 
 type (
@@ -32,6 +33,8 @@ type (
 		CustomGValSelector  bool `yaml:"customGValSelector"`
 		CustomSelector      bool `yaml:"customSelector"`
 		CustomFieldAssigner bool `yaml:"customFieldAssigner"`
+		Comparable          bool `yaml:"comparable"`
+		CustomComparator    bool `yaml:"customComparator"`
 		Struct              []*exprTypeStructDef
 
 		// @todo custom setters