gotohelm: fix map indexing and zeroOf

pkg/gotohelm/testdata/src/example/aaacommon/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/astrewrites/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/changing_inputs/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/directives/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/flowcontrol/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/inputs/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/k8s/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/k8s/k8s.go

@@ -181,9 +181,16 @@ func quantity(dot *helmette.Dot) map[string]any {
 		value = append(value, q.Value())
 	}
 
+	// Intentionally generate zero values of resource.Quantity to assert that
+	// zeroOf handles it.
+	var varZero resource.Quantity
+	resources := corev1.ResourceList{}
+
 	return map[string]any{
 		"MustParse": quantities,
 		"Value":     value,
 		"String":    strs,
+		"dictZero":  resources[corev1.ResourceCPU],
+		"varZero":   varZero,
 	}
 }

pkg/gotohelm/testdata/src/example/k8s/k8s.rewritten.go

@@ -182,9 +182,16 @@ func quantity(dot *helmette.Dot) map[string]any {
 		value = append(value, q.Value())
 	}
 
+	// Intentionally generate zero values of resource.Quantity to assert that
+	// zeroOf handles it.
+	var varZero resource.Quantity
+	resources := corev1.ResourceList{}
+
 	return map[string]any{
 		"MustParse": quantities,
 		"Value":     value,
 		"String":    strs,
+		"dictZero":  resources[corev1.ResourceCPU],
+		"varZero":   varZero,
 	}
 }

pkg/gotohelm/testdata/src/example/k8s/k8s.yaml

@@ -90,8 +90,10 @@
 {{- if $_is_returning -}}
 {{- break -}}
 {{- end -}}
+{{- $varZero := "0" -}}
+{{- $resources := (dict ) -}}
 {{- $_is_returning = true -}}
-{{- (dict "r" (dict "MustParse" $quantities "Value" $value "String" $strs )) | toJson -}}
+{{- (dict "r" (dict "MustParse" $quantities "Value" $value "String" $strs "dictZero" (ternary (index $resources "cpu") "0" (hasKey $resources "cpu")) "varZero" $varZero )) | toJson -}}
 {{- break -}}
 {{- end -}}
 {{- end -}}

pkg/gotohelm/testdata/src/example/labels/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/sprig/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/syntax/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/testdata/src/example/syntax/syntax.go

@@ -236,6 +236,12 @@ func binaryExprs() []any {
 		s1 + s2,
 		"one" + s2,
 		s1 + "two",
+		// Ensure that indexing into a map with a missing key generates the
+		// correct zero value.
+		map[string]int{}["missing"],
+		map[string]string{}["missing"],
+		map[string]bool{}["missing"],
+		map[string]struct{ Foo int }{}["missing"],
 	}
 }
 

pkg/gotohelm/testdata/src/example/syntax/syntax.rewritten.go

@@ -237,6 +237,12 @@ func binaryExprs() []any {
 		s1 + s2,
 		"one" + s2,
 		s1 + "two",
+		// Ensure that indexing into a map with a missing key generates the
+		// correct zero value.
+		map[string]int{}["missing"],
+		map[string]string{}["missing"],
+		map[string]bool{}["missing"],
+		map[string]struct{ Foo int }{}["missing"],
 	}
 }
 

pkg/gotohelm/testdata/src/example/syntax/syntax.yaml

@@ -212,7 +212,7 @@
 {{- $s1 := "one " -}}
 {{- $s2 := "two" -}}
 {{- $_is_returning = true -}}
-{{- (dict "r" (list (gt (1 | int) (2 | int)) (lt (1 | int) (2 | int)) (ge (1 | int) (2 | int)) (le (1 | int) (2 | int)) (ge (2 | int) (2 | int)) (le (2 | int) (2 | int)) (printf "%s%s" "string " "concatenation") (printf "%s%s" $s1 $s2) (printf "%s%s" "one" $s2) (printf "%s%s" $s1 "two"))) | toJson -}}
+{{- (dict "r" (list (gt (1 | int) (2 | int)) (lt (1 | int) (2 | int)) (ge (1 | int) (2 | int)) (le (1 | int) (2 | int)) (ge (2 | int) (2 | int)) (le (2 | int) (2 | int)) (printf "%s%s" "string " "concatenation") (printf "%s%s" $s1 $s2) (printf "%s%s" "one" $s2) (printf "%s%s" $s1 "two") (ternary (index (dict ) "missing") 0 (hasKey (dict ) "missing")) (ternary (index (dict ) "missing") "" (hasKey (dict ) "missing")) (ternary (index (dict ) "missing") false (hasKey (dict ) "missing")) (ternary (index (dict ) "missing") (dict "Foo" 0 ) (hasKey (dict ) "missing")))) | toJson -}}
 {{- break -}}
 {{- end -}}
 {{- end -}}

pkg/gotohelm/testdata/src/example/typing/_shims.tpl

@@ -301,7 +301,7 @@
 {{- $_ := (fail (printf "invalid Duration: %q" $original)) -}}
 {{- end -}}
 {{- $repr = (substr ((get (fromJson (include "_shims.len" (dict "a" (list $unit) ))) "r") | int) -1 $repr) -}}
-{{- $value = ((add $value (((mul (int64 $n) (index $unitMap $unit)) | int64))) | int64) -}}
+{{- $value = ((add $value (((mul (int64 $n) (ternary (index $unitMap $unit) 0 (hasKey $unitMap $unit))) | int64))) | int64) -}}
 {{- end -}}
 {{- if $_is_returning -}}
 {{- break -}}

pkg/gotohelm/transpiler.go

@@ -923,6 +923,46 @@ func (t *Transpiler) transpileExpr(n ast.Expr) Node {
 		}
 
 	case *ast.IndexExpr:
+		// IndexExprs handle (n.X)[n.Index] as an expression i.e. map tests (_,
+		// _ = X[Index]) are NOT handled here (see
+		// [Transpiler.transpileMVAssignStmt]).
+
+		switch typ := t.typeOf(n.X).Underlying().(type) {
+		case *types.Map:
+			// if the zero value of elem's type is NOT nil, we need to
+			// replicate go's behavior of returning zero values on missing
+			// keys.
+			elemZero := t.zeroOf(typ.Elem())
+			if _, ok := elemZero.(*Nil); !ok {
+				// This behavior is replicated using sprig's ternary function.
+				// Admittedly, this could cause unexpected behavior if either
+				// expr or index are particularly complex or have side effects.
+				// In practice, this, thankfully, has not been the case.
+				expr := t.transpileExpr(n.X)
+				index := t.transpileExpr(n.Index)
+
+				// X[index] -> (ternary (index X index) (zero) (hasKey X index))
+				return &BuiltInCall{
+					// Ternary signature is (trueVal, falseVal, testVal)
+					FuncName: "ternary",
+					Arguments: []Node{
+						&BuiltInCall{
+							FuncName:  "index",
+							Arguments: []Node{expr, index},
+						},
+						elemZero,
+						&BuiltInCall{
+							FuncName:  "hasKey",
+							Arguments: []Node{expr, index},
+						},
+					},
+				}
+			}
+		}
+
+		// Otherwise, text/template's builtin index function handles everything
+		// for us as it returns nil for missing keys due to all maps being
+		// `map[string]any`'s.
 		return &BuiltInCall{
 			FuncName: "index",
 			Arguments: []Node{
@@ -1419,9 +1459,6 @@ func (t *Transpiler) typeOf(expr ast.Expr) types.Type {
 }
 
 func (t *Transpiler) zeroOf(typ types.Type) Node {
-	// TODO need to detect and reject or special case implementors of
-	// json.Marshaler. Getting a handle to a that interface is... difficult.
-
 	// Special cases.
 	switch typ.String() {
 	case "k8s.io/apimachinery/pkg/apis/meta/v1.Time":
@@ -1430,6 +1467,30 @@ func (t *Transpiler) zeroOf(typ types.Type) Node {
 		// IntOrString's zero value appears to marshal to a 0 though it's
 		// unclear how correct this is.
 		return &Literal{Value: "0"}
+	case "k8s.io/apimachinery/pkg/api/resource.Quantity":
+		return &Literal{Value: `"0"`}
+	}
+
+	// If encoding/json is in the dependency chain for this package, we'll
+	// enable some additional checks (because it's other wise very difficult to
+	// check for implementation of {M,Unm}arshaller...)
+	if json, ok := t.packages["encoding/json"]; ok {
+		marshaller := json.Types.Scope().Lookup("Marshaler").Type().Underlying().(*types.Interface)
+		unmarshaller := json.Types.Scope().Lookup("Unmarshaler").Type().Underlying().(*types.Interface)
+
+		ptr := types.NewPointer(typ)
+
+		// If we can get a handle to Marshaler and Unmarshaler, we'll error out
+		// on any types that implement either and aren't special cased as their
+		// JSON representation likely won't match what we can infer from the go
+		// type.
+		switch {
+		case types.Implements(typ, unmarshaller),
+			types.Implements(typ, marshaller),
+			types.Implements(ptr, marshaller),
+			types.Implements(ptr, unmarshaller):
+			panic(fmt.Sprintf("unsupported type %q implemented json.Unmarshaler or json.Marshaller and needs to be special cased but isn't currently", typ.String()))
+		}
 	}
 
 	switch underlying := typ.Underlying().(type) {