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checks.go
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checks.go
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package compiler
import "fmt"
func checkRecursive(contract *Contract) bool {
for _, clause := range contract.Clauses {
for _, stmt := range clause.statements {
if l, ok := stmt.(*lockStatement); ok {
if c, ok := l.program.(*callExpr); ok {
if references(c.fn, contract.Name) {
return true
}
}
}
}
}
return false
}
func prohibitSigParams(contract *Contract) error {
for _, p := range contract.Params {
if p.Type == sigType {
return fmt.Errorf("contract parameter \"%s\" has type Signature, but contract parameters cannot have type Signature", p.Name)
}
}
return nil
}
func prohibitValueParams(contract *Contract) error {
for _, p := range contract.Params {
if p.Type == valueType {
return fmt.Errorf("Value-typed contract parameter \"%s\" must appear in a \"locks\" clause", p.Name)
}
}
for _, c := range contract.Clauses {
for _, p := range c.Params {
if p.Type == valueType {
return fmt.Errorf("Value-typed parameter \"%s\" of clause \"%s\" must appear in a \"requires\" clause", p.Name, c.Name)
}
}
}
return nil
}
func requireAllParamsUsedInClauses(params []*Param, clauses []*Clause) error {
for _, p := range params {
used := false
for _, c := range clauses {
err := requireAllParamsUsedInClause([]*Param{p}, c)
if err == nil {
used = true
break
}
}
if !used {
return fmt.Errorf("parameter \"%s\" is unused", p.Name)
}
}
return nil
}
func requireAllParamsUsedInClause(params []*Param, clause *Clause) error {
for _, p := range params {
used := false
for _, stmt := range clause.statements {
switch s := stmt.(type) {
case *verifyStatement:
used = references(s.expr, p.Name)
case *lockStatement:
used = references(s.locked, p.Name) || references(s.program, p.Name)
case *unlockStatement:
used = references(s.expr, p.Name)
}
if used {
break
}
}
if !used {
for _, r := range clause.Reqs {
if references(r.amountExpr, p.Name) || references(r.assetExpr, p.Name) {
used = true
break
}
}
}
if !used {
return fmt.Errorf("parameter \"%s\" is unused in clause \"%s\"", p.Name, clause.Name)
}
}
return nil
}
func references(expr expression, name string) bool {
switch e := expr.(type) {
case *binaryExpr:
return references(e.left, name) || references(e.right, name)
case *unaryExpr:
return references(e.expr, name)
case *callExpr:
if references(e.fn, name) {
return true
}
for _, a := range e.args {
if references(a, name) {
return true
}
}
return false
case varRef:
return string(e) == name
case listExpr:
for _, elt := range []expression(e) {
if references(elt, name) {
return true
}
}
return false
}
return false
}
func requireAllValuesDisposedOnce(contract *Contract, clause *Clause) error {
err := valueDisposedOnce(contract.Value, clause)
if err != nil {
return err
}
for _, req := range clause.Reqs {
err = valueDisposedOnce(req.Name, clause)
if err != nil {
return err
}
}
return nil
}
func valueDisposedOnce(name string, clause *Clause) error {
var count int
for _, s := range clause.statements {
switch stmt := s.(type) {
case *unlockStatement:
if references(stmt.expr, name) {
count++
}
case *lockStatement:
if references(stmt.locked, name) {
count++
}
}
}
switch count {
case 0:
return fmt.Errorf("value \"%s\" not disposed in clause \"%s\"", name, clause.Name)
case 1:
return nil
default:
return fmt.Errorf("value \"%s\" disposed multiple times in clause \"%s\"", name, clause.Name)
}
}
func referencedBuiltin(expr expression) *builtin {
if v, ok := expr.(varRef); ok {
for _, b := range builtins {
if string(v) == b.name {
return &b
}
}
}
return nil
}
func assignIndexes(clause *Clause) {
var nextIndex int64
for _, s := range clause.statements {
switch stmt := s.(type) {
case *lockStatement:
stmt.index = nextIndex
nextIndex++
case *unlockStatement:
nextIndex++
}
}
}
func typeCheckClause(contract *Contract, clause *Clause, env *environ) error {
for _, s := range clause.statements {
switch stmt := s.(type) {
case *verifyStatement:
if t := stmt.expr.typ(env); t != boolType {
return fmt.Errorf("expression in verify statement in clause \"%s\" has type \"%s\", must be Boolean", clause.Name, t)
}
case *lockStatement:
if t := stmt.locked.typ(env); t != valueType {
return fmt.Errorf("expression in lock statement in clause \"%s\" has type \"%s\", must be Value", clause.Name, t)
}
if t := stmt.program.typ(env); t != progType {
return fmt.Errorf("program in lock statement in clause \"%s\" has type \"%s\", must be Program", clause.Name, t)
}
case *unlockStatement:
if t := stmt.expr.typ(env); t != valueType {
return fmt.Errorf("expression \"%s\" in unlock statement of clause \"%s\" has type \"%s\", must be Value", stmt.expr, clause.Name, t)
}
if stmt.expr.String() != contract.Value {
return fmt.Errorf("expression in unlock statement of clause \"%s\" must be the contract value", clause.Name)
}
}
}
return nil
}