Object invariants (#62)

* Object invariants

desugarer.go

@@ -110,26 +110,23 @@ func desugarFields(location ast.LocationRange, fields *ast.ObjectFields, objLeve
 
 	// Simplify asserts
 	// TODO(dcunnin): this
-	for _, field := range *fields {
+	for i := range *fields {
+		field := &(*fields)[i]
 		if field.Kind != ast.ObjectAssert {
 			continue
 		}
-		/*
-			AST *msg = field.expr3
-			field.expr3 = nil
-			if (msg == nil) {
-				auto msg_str = U"Object assertion failed."
-				msg = alloc->make<ast.LiteralString>(field.expr2->location, msg_str,
-												 ast.LiteralString::DOUBLE, "")
-			}
-
-			// if expr2 then true else error msg
-			field.expr2 = alloc->make<ast.Conditional>(
-				ast->location,
-				field.expr2,
-				alloc->make<ast.LiteralBoolean>(E, true),
-				alloc->make<Error>(msg->location, msg))
-		*/
+		msg := field.Expr3
+		if msg == nil {
+			msg = buildLiteralString("Object assertion failed.")
+		}
+		field.Expr3 = nil
+		onFailure := &ast.Error{Expr: msg}
+		assertion := &ast.Conditional{
+			Cond:        field.Expr2,
+			BranchTrue:  &ast.LiteralBoolean{Value: true}, // ignored anyway
+			BranchFalse: onFailure,
+		}
+		field.Expr2 = assertion
 	}
 
 	// Remove methods

interpreter.go

@@ -326,8 +326,12 @@ func (i *interpreter) evaluate(a ast.Node, context *TraceContext) (value, error)
 			}
 			fields[fieldName] = valueSimpleObjectField{field.Hide, &codeUnboundField{field.Body}}
 		}
+		var asserts []unboundField
+		for _, assert := range ast.Asserts {
+			asserts = append(asserts, &codeUnboundField{assert})
+		}
 		upValues := i.capture(ast.FreeVariables())
-		return makeValueSimpleObject(upValues, fields, ast.Asserts), nil
+		return makeValueSimpleObject(upValues, fields, asserts), nil
 
 	case *ast.Error:
 		msgVal, err := e.evalInCurrentContext(ast.Expr)
@@ -570,6 +574,11 @@ func (i *interpreter) manifestJSON(trace *TraceElement, v value, multiline bool,
 		fieldNames := objectFields(v, true)
 		sort.Strings(fieldNames)
 
+		err := checkAssertions(e, v)
+		if err != nil {
+			return err
+		}
+
 		if len(fieldNames) == 0 {
 			buf.WriteString("{ }")
 		} else {

testdata/object_invariant.golden

@@ -0,0 +1 @@
+{ }

testdata/object_invariant.input

@@ -0,0 +1 @@
+{ assert true }

testdata/object_invariant10.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant10.input

@@ -0,0 +1 @@
+{ assert true, assert false }

testdata/object_invariant11.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant11.input

@@ -0,0 +1 @@
+{ assert false }.x

testdata/object_invariant12.golden

@@ -0,0 +1 @@
+{ }

testdata/object_invariant12.input

@@ -0,0 +1 @@
+{ assert 5 == 5 }

testdata/object_invariant13.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: x

testdata/object_invariant13.input

@@ -0,0 +1 @@
+{ assert error "x" }

testdata/object_invariant14.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: xxx

testdata/object_invariant14.input

@@ -0,0 +1 @@
+{ assert false: "xxx" }

testdata/object_invariant2.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant2.input

@@ -0,0 +1 @@
+{ assert false }

testdata/object_invariant3.golden

@@ -0,0 +1 @@
+[ ]

testdata/object_invariant3.input

@@ -0,0 +1 @@
+std.objectFields({assert false})

testdata/object_invariant4.golden

@@ -0,0 +1 @@
+false

testdata/object_invariant4.input

@@ -0,0 +1 @@
+std.objectHas({assert false}, "x")

testdata/object_invariant5.golden

@@ -0,0 +1 @@
+"object"

testdata/object_invariant5.input

@@ -0,0 +1 @@
+std.type({assert false})

testdata/object_invariant6.golden

@@ -0,0 +1,3 @@
+{
+   "x": 5
+}

testdata/object_invariant6.input

@@ -0,0 +1 @@
+{assert self.x == 5, x: 5}

testdata/object_invariant7.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Field does not exist: x

testdata/object_invariant7.input

@@ -0,0 +1 @@
+{ x: 5, assert super.x == 5 } 

testdata/object_invariant8.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant8.input

@@ -0,0 +1 @@
+{ x: 5, assert self.x == 4 }

testdata/object_invariant9.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant9.input

@@ -0,0 +1 @@
+{ assert true, assert false } 

testdata/object_invariant_perf.golden

@@ -0,0 +1,455 @@
+[
+   {
+      "v": -1
+   },
+   {
+      "v": 0
+   },
+   {
+      "v": 1
+   },
+   {
+      "v": 2
+   },
+   {
+      "v": 3
+   },
+   {
+      "v": 4
+   },
+   {
+      "v": 5
+   },
+   {
+      "v": 6
+   },
+   {
+      "v": 7
+   },
+   {
+      "v": 8
+   },
+   {
+      "v": 9
+   },
+   {
+      "v": 10
+   },
+   {
+      "v": 11
+   },
+   {
+      "v": 12
+   },
+   {
+      "v": 13
+   },
+   {
+      "v": 14
+   },
+   {
+      "v": 15
+   },
+   {
+      "v": 16
+   },
+   {
+      "v": 17
+   },
+   {
+      "v": 18
+   },
+   {
+      "v": 19
+   },
+   {
+      "v": 20
+   },
+   {
+      "v": 21
+   },
+   {
+      "v": 22
+   },
+   {
+      "v": 23
+   },
+   {
+      "v": 24
+   },
+   {
+      "v": 25
+   },
+   {
+      "v": 26
+   },
+   {
+      "v": 27
+   },
+   {
+      "v": 28
+   },
+   {
+      "v": 29
+   },
+   {
+      "v": 30
+   },
+   {
+      "v": 31
+   },
+   {
+      "v": 32
+   },
+   {
+      "v": 33
+   },
+   {
+      "v": 34
+   },
+   {
+      "v": 35
+   },
+   {
+      "v": 36
+   },
+   {
+      "v": 37
+   },
+   {
+      "v": 38
+   },
+   {
+      "v": 39
+   },
+   {
+      "v": 40
+   },
+   {
+      "v": 41
+   },
+   {
+      "v": 42
+   },
+   {
+      "v": 43
+   },
+   {
+      "v": 44
+   },
+   {
+      "v": 45
+   },
+   {
+      "v": 46
+   },
+   {
+      "v": 47
+   },
+   {
+      "v": 48
+   },
+   {
+      "v": 49
+   },
+   {
+      "v": 50
+   },
+   {
+      "v": 51
+   },
+   {
+      "v": 52
+   },
+   {
+      "v": 53
+   },
+   {
+      "v": 54
+   },
+   {
+      "v": 55
+   },
+   {
+      "v": 56
+   },
+   {
+      "v": 57
+   },
+   {
+      "v": 58
+   },
+   {
+      "v": 59
+   },
+   {
+      "v": 60
+   },
+   {
+      "v": 61
+   },
+   {
+      "v": 62
+   },
+   {
+      "v": 63
+   },
+   {
+      "v": 64
+   },
+   {
+      "v": 65
+   },
+   {
+      "v": 66
+   },
+   {
+      "v": 67
+   },
+   {
+      "v": 68
+   },
+   {
+      "v": 69
+   },
+   {
+      "v": 70
+   },
+   {
+      "v": 71
+   },
+   {
+      "v": 72
+   },
+   {
+      "v": 73
+   },
+   {
+      "v": 74
+   },
+   {
+      "v": 75
+   },
+   {
+      "v": 76
+   },
+   {
+      "v": 77
+   },
+   {
+      "v": 78
+   },
+   {
+      "v": 79
+   },
+   {
+      "v": 80
+   },
+   {
+      "v": 81
+   },
+   {
+      "v": 82
+   },
+   {
+      "v": 83
+   },
+   {
+      "v": 84
+   },
+   {
+      "v": 85
+   },
+   {
+      "v": 86
+   },
+   {
+      "v": 87
+   },
+   {
+      "v": 88
+   },
+   {
+      "v": 89
+   },
+   {
+      "v": 90
+   },
+   {
+      "v": 91
+   },
+   {
+      "v": 92
+   },
+   {
+      "v": 93
+   },
+   {
+      "v": 94
+   },
+   {
+      "v": 95
+   },
+   {
+      "v": 96
+   },
+   {
+      "v": 97
+   },
+   {
+      "v": 98
+   },
+   {
+      "v": 99
+   },
+   {
+      "v": 100
+   },
+   {
+      "v": 101
+   },
+   {
+      "v": 102
+   },
+   {
+      "v": 103
+   },
+   {
+      "v": 104
+   },
+   {
+      "v": 105
+   },
+   {
+      "v": 106
+   },
+   {
+      "v": 107
+   },
+   {
+      "v": 108
+   },
+   {
+      "v": 109
+   },
+   {
+      "v": 110
+   },
+   {
+      "v": 111
+   },
+   {
+      "v": 112
+   },
+   {
+      "v": 113
+   },
+   {
+      "v": 114
+   },
+   {
+      "v": 115
+   },
+   {
+      "v": 116
+   },
+   {
+      "v": 117
+   },
+   {
+      "v": 118
+   },
+   {
+      "v": 119
+   },
+   {
+      "v": 120
+   },
+   {
+      "v": 121
+   },
+   {
+      "v": 122
+   },
+   {
+      "v": 123
+   },
+   {
+      "v": 124
+   },
+   {
+      "v": 125
+   },
+   {
+      "v": 126
+   },
+   {
+      "v": 127
+   },
+   {
+      "v": 128
+   },
+   {
+      "v": 129
+   },
+   {
+      "v": 130
+   },
+   {
+      "v": 131
+   },
+   {
+      "v": 132
+   },
+   {
+      "v": 133
+   },
+   {
+      "v": 134
+   },
+   {
+      "v": 135
+   },
+   {
+      "v": 136
+   },
+   {
+      "v": 137
+   },
+   {
+      "v": 138
+   },
+   {
+      "v": 139
+   },
+   {
+      "v": 140
+   },
+   {
+      "v": 141
+   },
+   {
+      "v": 142
+   },
+   {
+      "v": 143
+   },
+   {
+      "v": 144
+   },
+   {
+      "v": 145
+   },
+   {
+      "v": 146
+   },
+   {
+      "v": 147
+   },
+   {
+      "v": 148
+   },
+   {
+      "v": 149
+   }
+]

testdata/object_invariant_perf.input

@@ -0,0 +1,2 @@
+local arr = [{v: -1}] + std.makeArray(150, function(x) { v: x, assert arr[x].v == self.v - 1 });
+arr

testdata/object_invariant_plus.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant_plus.input

@@ -0,0 +1 @@
+{assert false} + {assert true}

testdata/object_invariant_plus2.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Object assertion failed.

testdata/object_invariant_plus2.input

@@ -0,0 +1 @@
+{assert true} + {assert false}

testdata/object_invariant_plus3.golden

@@ -0,0 +1 @@
+{ }

testdata/object_invariant_plus3.input

@@ -0,0 +1 @@
+{assert true} + {assert true}

testdata/object_invariant_plus4.golden

@@ -0,0 +1,3 @@
+{
+   "x": 5
+}

testdata/object_invariant_plus4.input

@@ -0,0 +1 @@
+{assert self.x == 5} { x: 5 } 

testdata/object_invariant_plus5.golden

@@ -0,0 +1,3 @@
+{
+   "x": 3
+}

testdata/object_invariant_plus5.input

@@ -0,0 +1 @@
+{x: 1, assert self.x == 3} {x: 2, assert super.x == 1} {x: 3, assert super.x == 2}

testdata/object_invariant_plus6.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: yyy

testdata/object_invariant_plus6.input

@@ -0,0 +1 @@
+{ assert false: "xxx" } { assert false: "yyy" }

testdata/object_invariant_plus7.golden

@@ -0,0 +1,3 @@
+{
+   "x": 4
+}

testdata/object_invariant_plus7.input

@@ -0,0 +1,2 @@
+({x: 1} {x: 2, assert 1 == super.x}) +
+({x: 3, assert 2 == super.x} {x: 4, assert 3 == super.x})

testdata/std.makeArray_recursive.input

@@ -0,0 +1 @@
+local arr = [0] + std.makeArray(2000, function(i) arr[i] + 1); arr

testdata/std.makeArray_recursive_evalutation_order_matters.golden

@@ -0,0 +1 @@
+RUNTIME ERROR: Max stack frames exceeded.

testdata/std.makeArray_recursive_evalutation_order_matters.input

@@ -0,0 +1 @@
+local arr = [0] + std.makeArray(2000, function(i) arr[i] + 1); arr[500]

thunks.go

@@ -75,7 +75,7 @@ type callThunk struct {
 }
 
 func makeCallThunk(ec evalCallable, args callArguments) potentialValue {
-	return &callThunk{function: ec, args: args}
+	return makeCachedThunk(&callThunk{function: ec, args: args})
 }
 
 func (th *callThunk) getValue(i *interpreter, trace *TraceElement) (value, error) {

value.go

@@ -16,6 +16,7 @@ limitations under the License.
 package jsonnet
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/google/go-jsonnet/ast"
@@ -269,6 +270,9 @@ type valueObject interface {
 	value
 	inheritanceSize() int
 	index(e *evaluator, field string) (value, error)
+	assertionsChecked() bool
+	setAssertionsCheckResult(err error)
+	getAssertionsCheckResult() error
 }
 
 type selfBinding struct {
@@ -276,7 +280,7 @@ type selfBinding struct {
 	// that this is not the same as context, because we could be inside a function,
 	// inside an object and then context would be the function, but self would still point
 	// to the object.
-	self value
+	self valueObject
 
 	// superDepth is the "super" level of self.  Sometimes, we look upwards in the
 	// inheritance tree, e.g. via an explicit use of super, or because a given field
@@ -297,14 +301,43 @@ func makeUnboundSelfBinding() selfBinding {
 	}
 }
 
+// Hack - we need to distinguish not-checked-yet and no error situations
+// so we have a special value for no error and nil means that we don't know yet.
+var errNoErrorInObjectInvariants = errors.New("No error - assertions passed")
+
 type valueObjectBase struct {
 	valueBase
+	assertionError error
 }
 
 func (*valueObjectBase) typename() string {
 	return "object"
 }
 
+func (obj *valueObjectBase) assertionsChecked() bool {
+	// nil - not checked yet
+	// errNoErrorInObjectInvariants - we checked and there is no error (or checking in progress)
+	return obj.assertionError != nil
+}
+
+func (obj *valueObjectBase) setAssertionsCheckResult(err error) {
+	if err != nil {
+		obj.assertionError = err
+	} else {
+		obj.assertionError = errNoErrorInObjectInvariants
+	}
+}
+
+func (obj *valueObjectBase) getAssertionsCheckResult() error {
+	if obj.assertionError == nil {
+		panic("Assertions not checked yet")
+	}
+	if obj.assertionError == errNoErrorInObjectInvariants {
+		return nil
+	}
+	return obj.assertionError
+}
+
 // valueSimpleObject represents a flat object (no inheritance).
 // Note that it can be used as part of extended objects
 // in inheritance using operator +.
@@ -317,7 +350,43 @@ type valueSimpleObject struct {
 	valueObjectBase
 	upValues bindingFrame
 	fields   valueSimpleObjectFieldMap
-	asserts  []ast.Node
+	asserts  []unboundField
+}
+
+func checkAssertionsHelper(e *evaluator, obj valueObject, curr valueObject, superDepth int) error {
+	switch curr := curr.(type) {
+	case *valueExtendedObject:
+		err := checkAssertionsHelper(e, obj, curr.right, superDepth)
+		if err != nil {
+			return err
+		}
+		err = checkAssertionsHelper(e, obj, curr.left, superDepth+curr.right.inheritanceSize())
+		if err != nil {
+			return err
+		}
+		return nil
+	case *valueSimpleObject:
+		for _, assert := range curr.asserts {
+			_, err := e.evaluate(assert.bindToObject(selfBinding{self: obj, superDepth: superDepth}, curr.upValues))
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	default:
+		panic(fmt.Sprintf("Unknown object type %#v", obj))
+	}
+}
+
+func checkAssertions(e *evaluator, obj valueObject) error {
+	if !obj.assertionsChecked() {
+		// Assertions may refer to the object that will normally
+		// trigger checking of assertions, resulting in an endless recursion.
+		// To avoid that, while we check them, we treat them as already passed.
+		obj.setAssertionsCheckResult(errNoErrorInObjectInvariants)
+		obj.setAssertionsCheckResult(checkAssertionsHelper(e, obj, obj, 0))
+	}
+	return obj.getAssertionsCheckResult()
 }
 
 func (o *valueSimpleObject) index(e *evaluator, field string) (value, error) {
@@ -328,7 +397,7 @@ func (*valueSimpleObject) inheritanceSize() int {
 	return 1
 }
 
-func makeValueSimpleObject(b bindingFrame, fields valueSimpleObjectFieldMap, asserts ast.Nodes) *valueSimpleObject {
+func makeValueSimpleObject(b bindingFrame, fields valueSimpleObjectFieldMap, asserts []unboundField) *valueSimpleObject {
 	return &valueSimpleObject{
 		upValues: b,
 		fields:   fields,
@@ -425,6 +494,10 @@ func superIndex(e *evaluator, currentSB selfBinding, field string) (value, error
 }
 
 func objectIndex(e *evaluator, sb selfBinding, fieldName string) (value, error) {
+	err := checkAssertions(e, sb.self)
+	if err != nil {
+		return nil, err
+	}
 	field, upValues, foundAt := findField(sb.self, sb.superDepth, fieldName)
 	if field == nil {
 		return nil, e.Error(fmt.Sprintf("Field does not exist: %s", fieldName))