feat: conversion between jsonlogic and nikunjy/rules expression

Author: ahuangg

converter/converter.go

@@ -0,0 +1,212 @@
+package converter
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// JSONToExpression parses jsonlogic in string format to an expression
+// compatible with nikunjy/rules engine
+func JSONToExpression(jsonLogic string) (string, error) {
+	var logicTree map[string]interface{}
+	if err := json.Unmarshal([]byte(jsonLogic), &logicTree); err != nil {
+		return "", err
+	}
+	return parseLogicTree(logicTree), nil
+}
+
+func parseLogicTree(node map[string]interface{}) string {
+	for _, key := range []string{"and", "or"} {
+		if rulesList, ok := node[key].([]interface{}); ok {
+			rules := make([]string, len(rulesList))
+			for i, r := range rulesList {
+				rules[i] = parseLogicTree(r.(map[string]interface{}))
+			}
+			return "(" + strings.Join(rules, " "+key+" ") + ")"
+		}
+	}
+
+	for op, value := range node {
+		values := value.([]interface{})
+		left := values[0]
+		if m, ok := left.(map[string]interface{}); ok {
+			left = m["var"]
+		}
+		return "(" + fmt.Sprintf("%v %s %v", left, op, values[1]) + ")"
+	}
+
+	return ""
+}
+
+ 
+// ExpressionToJSON parses a nikunjy/rules expression to jsonLogic
+func ExpressionToJSON(expression string) (string, error) {
+	tokens := strings.Fields(expression)
+
+	logicTree, err := buildLogicTree(tokens)
+	if err != nil {
+		return "", err
+	}
+
+	buf := new(bytes.Buffer)
+	enc := json.NewEncoder(buf)
+	enc.SetEscapeHTML(false)
+	
+	if err := enc.Encode(logicTree); err != nil {
+		return "", err
+	}
+	
+	return strings.TrimSpace(buf.String()), nil
+}
+
+func buildLogicTree(tokens []string) (map[string]interface{}, error) {
+    var nodes []interface{}
+    var logicalOperator string
+
+    for i := 0; i < len(tokens); i++ {
+        token := tokens[i]
+
+        switch token {
+        case "(":
+            expression, tokensProcessed, err := parseParenExpression(tokens[i:])
+            if err != nil {
+                return nil, err
+            }
+            nodes = append(nodes, expression)
+            i += tokensProcessed
+        case "and", "or":
+            logicalOperator = token
+        case "not":
+            expression, tokensProcessed, err := parseNotExpression(tokens[i:])
+            if err != nil {
+                return nil, err
+            }
+            nodes = append(nodes, expression)
+            i += tokensProcessed
+        default:
+            expression, err := parseComparisonExpression(tokens[i:])
+            if err != nil {
+                return nil, err
+            }
+            nodes = append(nodes, expression)
+            i += 2
+        }
+    }
+
+    if len(nodes) == 1 {
+        return nodes[0].(map[string]interface{}), nil
+    }
+
+    return map[string]interface{}{
+        logicalOperator: nodes,
+    }, nil
+}
+
+func parseParenExpression(tokens []string) (map[string]interface{}, int, error) {
+    level := 1
+    end := 1
+
+    for level > 0 && end < len(tokens) {
+        if tokens[end] == "(" {
+            level++
+        } else if tokens[end] == ")" {
+            level--
+        }
+        end++
+    }
+    if level != 0 {
+        return nil, 0, fmt.Errorf("invalid expression")
+    }
+
+    expression, err := buildLogicTree(tokens[1 : end-1])
+    if err != nil {
+        return nil, 0, err
+    }
+
+    return expression, end - 1, nil
+}
+
+func parseNotExpression(tokens []string) (map[string]interface{}, int, error) {
+    if len(tokens) < 2 {
+        return nil, 0, fmt.Errorf("invalid expression")
+    }
+
+    if tokens[1] == "(" {
+        subExpr, newIndex, err := parseParenExpression(tokens[1:])
+        if err != nil {
+            return nil, 0, err
+        }
+        return map[string]interface{}{"!": subExpr}, newIndex + 1, nil
+    }
+	
+	if len(tokens) >= 4 && isComparisonOperator(tokens[2]) {
+        return map[string]interface{}{
+            "!": map[string]interface{}{
+                tokens[2]: []interface{}{
+                    map[string]interface{}{"var": tokens[1]},
+                    parseValue(tokens[3]),
+                },
+            },
+        }, 3, nil
+    }
+
+    return map[string]interface{}{
+        "!": map[string]interface{}{"var": tokens[1]},
+    }, 1, nil
+}
+func isComparisonOperator(op string) bool {
+    switch op {
+    case "eq", "==",
+         "ne", "!=",
+         "lt", "<",
+         "gt", ">", 
+         "le", "<=",
+         "ge", ">=",
+         "co", "sw", "ew",
+         "in", "pr":
+        return true
+    }
+    return false
+}
+
+func parseComparisonExpression(tokens []string) (map[string]interface{}, error) {
+    if len(tokens) < 3 {
+        return nil, fmt.Errorf("invalid expression")
+    }
+
+    varName := strings.Trim(tokens[0], "()")
+    value := strings.Trim(tokens[2], "()")
+
+    return map[string]interface{}{
+        tokens[1]: []interface{}{
+            map[string]interface{}{"var": varName},
+            parseValue(value),
+        },
+    }, nil
+}
+
+func parseValue(val string) interface{} {
+    if strings.HasPrefix(val, "[") && strings.HasSuffix(val, "]") {
+        items := strings.Split(strings.Trim(val, "[]"), ",")
+        var result []interface{}
+
+        for _, item := range items {
+            item = strings.TrimSpace(item)
+            if num, err := strconv.Atoi(item); err == nil {
+                result = append(result, num)
+            } else {
+                result = append(result, strings.Trim(item, "\"'"))
+            }
+        }
+        return result
+    }
+
+    if num, err := strconv.Atoi(val); err == nil {
+        return num
+    }
+
+    return strings.Trim(val, "\"'")
+}

test/converter/converter_test.go

@@ -0,0 +1,154 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/ahuangg/json-rules/converter"
+)
+
+
+func TestJSONToExpression(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+		wantErr  bool
+	}{
+		{
+			name:     "equal test",
+			input:    `{"eq": [{"var": "x"}, 1]}`,
+			expected: "(x eq 1)",
+		},
+		{
+			name:     "equal test 2",
+			input:    `{"==": [{"var": "x"}, 2]}`,
+			expected: "(x == 2)",
+		},
+		{
+			name:     "less than test",
+			input:    `{"<": [{"var": "x"}, 2]}`,
+			expected: "(x < 2)",
+		},
+		{
+			name:     "less than test 2",
+			input:    `{"<": [{"var": "x"}, 1]}`,
+			expected: "(x < 1)",
+		},
+		{
+			name:     "greater than test",
+			input:    `{">": [{"var": "x"}, 0]}`,
+			expected: "(x > 0)",
+		},
+		{
+			name:     "greater than test 2",
+			input:    `{">": [{"var": "x"}, 2]}`,
+			expected: "(x > 2)",
+		},
+		{
+			name:     "equal and less than equal test",
+			input:    `{"and": [{"==": [{"var": "x.a"}, 1]}, {"<=": [{"var": "x.b.c"}, 2]}]}`,
+			expected: "((x.a == 1) and (x.b.c <= 2))",
+		},
+		{
+			name:     "equal and greater than test",
+			input:    `{"and": [{"==": [{"var": "y"}, 4]}, {">": [{"var": "x"}, 1]}]}`,
+			expected: "((y == 4) and (x > 1))",
+		},
+		{
+			name:     "in test",
+			input:    `{"and": [{"==": [{"var": "y"}, 4]}, {"in": [{"var": "x"}, [1, 2, 3]]}]}`,
+			expected: "((y == 4) and (x in [1 2 3]))",
+		},
+		{
+			name:     "equal string test",
+			input:    `{"and": [{"==": [{"var": "y"}, 4]}, {"eq": [{"var": "x"}, "1.2.3"]}]}`,
+			expected: `((y == 4) and (x eq 1.2.3))`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := converter.JSONToExpression(tt.input)
+			if err != nil {
+				return
+			} 
+
+			if got != tt.expected {
+				t.Errorf("JSONToExpression() = %v, want %v", got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestExpressionToJSON(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+		wantErr  bool
+	}{
+		{
+			name:     "equal test",
+			input:    "x eq 1",
+			expected: `{"eq":[{"var":"x"},1]}`,
+		},
+		{
+			name:     "equal test 2", 
+			input:    "x == 2",
+			expected: `{"==":[{"var":"x"},2]}`,
+		},
+		{
+			name:     "less than test",
+			input:    "x < 2",
+			expected: `{"<":[{"var":"x"},2]}`,
+		},
+		{
+			name:     "less than test 2",
+			input:    "x < 1",
+			expected: `{"<":[{"var":"x"},1]}`,
+		},
+		{
+			name:     "greater than test",
+			input:    "x > 0",
+			expected: `{">":[{"var":"x"},0]}`,
+		},
+		{
+			name:     "greater than test 2",
+			input:    "x > 2",
+			expected: `{">":[{"var":"x"},2]}`,
+		},
+		{
+			name:     "equal and less than equal test",
+			input:    "((x.a == 1) and (x.b.c <= 2))",
+			expected: `{"and":[{"==":[{"var":"x.a"},1]},{"<=":[{"var":"x.b.c"},2]}]}`,
+		},
+		{
+			name:     "equal and greater than test",
+			input:    "y == 4 and (x > 1)",
+			expected: `{"and":[{"==":[{"var":"y"},4]},{">":[{"var":"x"},1]}]}`,
+		},
+		{
+			name:     "in test",
+			input:    "y == 4 and (x in [1 2 3])",
+			expected: `{"and":[{"==":[{"var":"y"},4]},{"in":[{"var":"x"},[1,2,3]]}]}`,
+		},
+		{
+			name:     "equal string test",
+			input:    `y == 4 and (x eq 1.2.3)`,
+			expected: `{"and":[{"==":[{"var":"y"},4]},{"eq":[{"var":"x"},"1.2.3"]}]}`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := converter.ExpressionToJSON(tt.input)
+			if err != nil {
+				return
+			}
+
+			if got != tt.expected {
+				t.Errorf("ExpressionToJSON() = %v, want %v", got, tt.expected)
+			}
+		})
+	}
+}