feat(func): add reverse function

Signed-off-by: Dream95 <[email protected]>
lf-edge · Nov 5, 2024 · 9f213d8 · 9f213d8
1 parent 31e0b4c
commit 9f213d8
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Showing 3 changed files with 66 additions and 3 deletions.
diff --git a/etc/functions/internal.json b/etc/functions/internal.json
@@ -1149,10 +1149,10 @@
 			"category": "function",
 			"icon": "iconPath",
 			"label": {
-					"en_US": "Natural Logarithm",
-					"zh_CN": "自然对数"
-				}
+				"en_US": "Natural Logarithm",
+				"zh_CN": "自然对数"
 			}
+		}
 	}, {
 		"name": "log",
 		"example": "log(col1)",
@@ -2137,6 +2137,44 @@
 				"zh_CN": "正则匹配子串"
 			}
 		}
+	},{
+		"name": "reverse",
+		"example": "reverse(col1)",
+		"hint": {
+			"en_US": "Returns the reversed string.",
+			"zh_CN": "返回反转的字符串。"
+		},
+		"args": [
+			{
+				"name": "string",
+				"optional": false,
+				"control": "field",
+				"type": "string",
+				"hint": {
+					"en_US": "A String",
+					"zh_CN": "String 值"
+				},
+				"label": {
+					"en_US": "String",
+					"zh_CN": "String 值"
+				}
+			}
+		],
+		"return": {
+			"type": "string",
+			"hint": {
+				"en_US": "Reversed String",
+				"zh_CN": "反转的字符串"
+			}
+		},
+		"node": {
+			"category": "function",
+			"icon": "iconPath",
+			"label": {
+				"en_US": "Reverse",
+				"zh_CN": "反转字符串"
+			}
+		}
 	}, {
 		"name": "rpad",
 		"example": "rpad(col1, 2)",

diff --git a/internal/binder/function/funcs_str.go b/internal/binder/function/funcs_str.go
@@ -181,6 +181,19 @@ func registerStrFunc() {
 		val:   ValidateTwoStrArg,
 		check: returnNilIfHasAnyNil,
 	}
+	builtins["reverse"] = builtinFunc{
+		fType: ast.FuncTypeScalar,
+		exec: func(ctx api.FunctionContext, args []interface{}) (interface{}, bool) {
+			arg0 := cast.ToStringAlways(args[0])
+			runes := []rune(arg0)
+			for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
+				runes[i], runes[j] = runes[j], runes[i]
+			}
+			return string(runes), true
+		},
+		val:   ValidateOneStrArg,
+		check: returnNilIfHasAnyNil,
+	}
 	builtins["rpad"] = builtinFunc{
 		fType: ast.FuncTypeScalar,
 		exec: func(ctx api.FunctionContext, args []interface{}) (interface{}, bool) {

diff --git a/internal/topo/operator/str_func_test.go b/internal/topo/operator/str_func_test.go
@@ -392,6 +392,18 @@ func TestStrFunc_Apply1(t *testing.T) {
 			},
 			result: []map[string]interface{}{{}},
 		},
+		{
+			sql: "SELECT reverse(a) AS a FROM test",
+			data: &xsql.Tuple{
+				Emitter: "test",
+				Message: xsql.Message{
+					"a": "abc",
+				},
+			},
+			result: []map[string]interface{}{{
+				"a": "cba",
+			}},
+		},
 		{
 			sql: "SELECT rpad(a, 3) AS a FROM test",
 			data: &xsql.Tuple{