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ast: Fix rewriting vars in rule args #2082

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merged 1 commit into from
Feb 9, 2020
Merged

ast: Fix rewriting vars in rule args #2082

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72 changes: 66 additions & 6 deletions ast/compile.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1092,7 +1092,10 @@ func (c *Compiler) rewriteLocalVars() {
}

stack := newLocalDeclaredVars()
body, declared, errs := rewriteLocalVars(gen, stack, rule.Head.Args.Vars(), used, rule.Body)

c.rewriteLocalArgVars(gen, stack, rule)

body, declared, errs := rewriteLocalVars(gen, stack, used, rule.Body)
for _, err := range errs {
c.err(err)
}
Expand Down Expand Up @@ -1151,6 +1154,66 @@ func (c *Compiler) rewriteLocalVars() {
}
}

func (c *Compiler) rewriteLocalArgVars(gen *localVarGenerator, stack *localDeclaredVars, rule *Rule) {

vis := &ruleArgLocalRewriter{
stack: stack,
gen: gen,
}

for i := range rule.Head.Args {
Walk(vis, rule.Head.Args[i])
}

for i := range vis.errs {
c.err(vis.errs[i])
}
}

type ruleArgLocalRewriter struct {
stack *localDeclaredVars
gen *localVarGenerator
errs []*Error
}

func (vis *ruleArgLocalRewriter) Visit(x interface{}) Visitor {

t, ok := x.(*Term)
if !ok {
return vis
}

switch v := t.Value.(type) {
case Var:
gv, ok := vis.stack.Declared(v)
if !ok {
gv = vis.gen.Generate()
vis.stack.Insert(v, gv, argVar)
}
t.Value = gv
return nil
case Object:
if cpy, err := v.Map(func(k, v *Term) (*Term, *Term, error) {
vcpy := v.Copy()
Walk(vis, vcpy)
return k, vcpy, nil
}); err != nil {
vis.errs = append(vis.errs, NewError(CompileErr, t.Location, err.Error()))
} else {
t.Value = cpy
}
return nil
case Null, Boolean, Number, String, *ArrayComprehension, *SetComprehension, *ObjectComprehension, Set:
// Scalars are no-ops. Comprehensions are handled above. Sets must not
// contain variables.
return nil
default:
// Recurse on refs, arrays, and calls. Any embedded
// variables can be rewritten.
return vis
}
}

func (c *Compiler) rewriteWithModifiers() {
f := newEqualityFactory(c.localvargen)
for _, name := range c.sorted {
Expand Down Expand Up @@ -1333,7 +1396,7 @@ func (qc *queryCompiler) rewriteExprTerms(_ *QueryContext, body Body) (Body, err
func (qc *queryCompiler) rewriteLocalVars(_ *QueryContext, body Body) (Body, error) {
gen := newLocalVarGenerator("q", body)
stack := newLocalDeclaredVars()
body, _, err := rewriteLocalVars(gen, stack, nil, nil, body)
body, _, err := rewriteLocalVars(gen, stack, nil, body)
if len(err) != 0 {
return nil, err
}
Expand Down Expand Up @@ -2910,10 +2973,7 @@ func (s localDeclaredVars) Occurrence(x Var) varOccurrence {
// __local0__ = 1; p[__local0__]
//
// During rewriting, assignees are validated to prevent use before declaration.
func rewriteLocalVars(g *localVarGenerator, stack *localDeclaredVars, args VarSet, used VarSet, body Body) (Body, map[Var]Var, Errors) {
for v := range args {
stack.Insert(v, v, argVar)
}
func rewriteLocalVars(g *localVarGenerator, stack *localDeclaredVars, used VarSet, body Body) (Body, map[Var]Var, Errors) {
var errs Errors
body, errs = rewriteDeclaredVarsInBody(g, stack, used, body, errs)
return body, stack.Pop().vs, errs
Expand Down
72 changes: 59 additions & 13 deletions ast/compile_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -956,17 +956,17 @@ func TestCompilerRewriteExprTerms(t *testing.T) {
expected := MustParseModule(`
package test

p { mul(b, y, __local0__); plus(a, __local0__, __local1__); eq(x, __local1__) }
p { mul(b, y, __local1__); plus(a, __local1__, __local2__); eq(x, __local2__) }

q[[__local2__]] { x = 1; data.test.f(x, __local2__) }
q[[__local3__]] { x = 1; data.test.f(x, __local3__) }

r = [__local3__] { x = 1; data.test.f(x, __local3__) }
r = [__local4__] { x = 1; data.test.f(x, __local4__) }

f(x) = __local4__ { true; data.test.g(x, __local4__) }
f(__local0__) = __local5__ { true; data.test.g(__local0__, __local5__) }

pi = __local5__ { true; plus(3, 0.14, __local5__) }
pi = __local6__ { true; plus(3, 0.14, __local6__) }

with_value { data.test.f(1, __local6__); 1 with input as __local6__ }
with_value { data.test.f(1, __local7__); 1 with input as __local7__ }
`)

if !expected.Equal(compiler.Modules["test"]) {
Expand Down Expand Up @@ -1233,7 +1233,7 @@ func TestCompilerRewriteLocalAssignments(t *testing.T) {

tests := []struct {
module string
exp string
exp interface{}
expRewrittenMap map[Var]Var
}{
{
Expand All @@ -1256,10 +1256,11 @@ func TestCompilerRewriteLocalAssignments(t *testing.T) {
`,
exp: `
package test
head_vars(a) = __local0__ { __local0__ = a }
head_vars(__local0__) = __local1__ { __local1__ = __local0__ }
`,
expRewrittenMap: map[Var]Var{
Var("__local0__"): Var("b"),
Var("__local0__"): Var("a"),
Var("__local1__"): Var("b"),
},
},
{
Expand Down Expand Up @@ -1580,16 +1581,53 @@ func TestCompilerRewriteLocalAssignments(t *testing.T) {
y := 4
}
`,
// Each "else" rule has a separate rule head and the vars in the
// args will be rewritten. Since we cannot currently redefine the
// args, we must parse the module and then manually update the args.
exp: func() *Module {
module := MustParseModule(`
package test

f(__local0__) = __local1__ { __local0__ == 1; __local1__ = 2 } else = __local3__ { __local2__ == 3; __local3__ = 4 }
`)
module.Rules[0].Else.Head.Args[0].Value = Var("__local2__")
return module
},
expRewrittenMap: map[Var]Var{
Var("__local0__"): Var("x"),
Var("__local1__"): Var("y"),
Var("__local2__"): Var("x"),
Var("__local3__"): Var("y"),
},
},
{
module: `
package test
f({"x": [x]}) = y { x == 1; y := 2 }`,
exp: `
package test

f(x) = __local0__ { x == 1; __local0__ = 2 } else = __local1__ { x == 3; __local1__ = 4 }
`,
f({"x": [__local0__]}) = __local1__ { __local0__ == 1; __local1__ = 2 }`,
expRewrittenMap: map[Var]Var{
Var("__local0__"): Var("y"),
Var("__local0__"): Var("x"),
Var("__local1__"): Var("y"),
},
},
{
module: `
package test

f(x, [x]) = x { x == 1 }
`,
exp: `
package test

f(__local0__, [__local0__]) = __local0__ { __local0__ == 1 }
`,
expRewrittenMap: map[Var]Var{
Var("__local0__"): Var("x"),
},
},
}

for i, tc := range tests {
Expand All @@ -1601,7 +1639,15 @@ func TestCompilerRewriteLocalAssignments(t *testing.T) {
compileStages(c, c.rewriteLocalVars)
assertNotFailed(t, c)
result := c.Modules["test.rego"]
exp := MustParseModule(tc.exp)
var exp *Module
switch e := tc.exp.(type) {
case string:
exp = MustParseModule(e)
case func() *Module:
exp = e()
default:
panic("expected value must be string or func() *Module")
}
if result.Compare(exp) != 0 {
t.Fatalf("\nExpected:\n\n%v\n\nGot:\n\n%v", exp, result)
}
Expand Down