empty-slice iterate

go/reg-test/cases/case-slice.sh

@@ -1,4 +1,4 @@
-mlr -n --ojson put '
+run_mlr -n --ojson put '
   end {
     a = [1,2,3,4,5,6,7];
     m = {"a": 1, "b": 2};

go/reg-test/expected/case-go-dsl-substr.sh.out

@@ -21,7 +21,7 @@ mlr put $y = substr($x, 3, 3)
 x=abcdefg,y=c
 
 mlr put $y = substr($x, 4, 3)
-x=abcdefg,y=
+x=abcdefg,y=(error)
 
 mlr put $y = substr($x, 2, 5)
 x=1234567,y=2345

go/reg-test/expected/case-slice.sh.out

@@ -1 +1,73 @@
 
+mlr -n --ojson put 
+  end {
+    a = [1,2,3,4,5,6,7];
+    m = {"a": 1, "b": 2};
+    s = "abcdefg";
+
+    emit {
+      "a35": a[3:5],
+      "a37": a[3:7],
+      "a17": a[1:7],
+      "a07": a[0:7],
+      "a39": a[3:9],
+      "a53": a[5:3],
+      "a93": a[9:3],
+    };
+
+    emit {
+      "m11": m[1:1],
+    };
+
+    emit {
+      "s35": s[3:5],
+      "s37": s[3:7],
+      "s17": s[1:7],
+      "s07": s[0:7],
+      "s39": s[3:9],
+      "s53": s[5:3],
+      "s93": s[9:3],
+    };
+
+    emit {
+      "u35": substr(s,3,5),
+      "u37": substr(s,3,7),
+      "u17": substr(s,1,7),
+      "u07": substr(s,0,7),
+      "u39": substr(s,3,9),
+      "u53": substr(s,5,3),
+      "u93": substr(s,9,3),
+    };
+  }
+
+{
+  "a35": [3, 4, 5],
+  "a37": [3, 4, 5, 6, 7],
+  "a17": [1, 2, 3, 4, 5, 6, 7],
+  "a07": (error),
+  "a39": (error),
+  "a53": [],
+  "a93": (error)
+}
+{
+  "m11": (error)
+}
+{
+  "s35": "cde",
+  "s37": "cdefg",
+  "s17": "abcdefg",
+  "s07": "",
+  "s39": "",
+  "s53": (error),
+  "s93": ""
+}
+{
+  "u35": "cde",
+  "u37": "cdefg",
+  "u17": "abcdefg",
+  "u07": "",
+  "u39": "",
+  "u53": (error),
+  "u93": ""
+}
+

go/src/miller/dsl/cst/collections.go

@@ -155,11 +155,19 @@ func (this *ArraySliceAccessNode) Evaluate(state *State) types.Mlrval {
 
 	lowerIndex, ok := lowerIndexMlrval.GetIntValue()
 	if !ok {
-		return types.MlrvalFromError()
+		if lowerIndexMlrval.IsEmpty() {
+			lowerIndex = 1
+		} else {
+			return types.MlrvalFromError()
+		}
 	}
 	upperIndex, ok := upperIndexMlrval.GetIntValue()
 	if !ok {
-		return types.MlrvalFromError()
+		if upperIndexMlrval.IsEmpty() {
+			upperIndex = int64(len(array))
+		} else {
+			return types.MlrvalFromError()
+		}
 	}
 
 	lowerZindex, ok := types.UnaliasArrayIndex(&array, lowerIndex)

go/todo.txt

@@ -5,6 +5,7 @@ small:
 * justWroteEmptyLine -> pprint too ...
 ! nidx @ 10-min
 ! text-put @ 10-min
+! slice: empty lower/higher
 
 medium:
 ! gating after: 'int x = 1; x = "abc"'
@@ -377,3 +378,4 @@ NITS/NON-IMMEDIATE:
   o ....
   o put '$array = [1,2,3,[4,5]]' is a syntax error unfortunately; need '$array = [1,2,3,[4,5] ]'
 * doc: string index/slice access on RHS
+* substr(7,5) -- "" or error?