Populate exception variable value in catch blocks
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parent
240a08b73e
commit
43556de6d7
2 changed files with 61 additions and 41 deletions
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@ -56,6 +56,18 @@ func (e *evaluator) EvaluatePackage(pkg *pack.Package) graph.Graph {
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return nil
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}
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// Utility functions
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func (e *evaluator) pushScope() {
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e.locals.Push() // for local variables
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e.ctx.Scope.Pop() // for symbol bindings
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}
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func (e *evaluator) popScope() {
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e.locals.Pop() // for local variables.
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e.ctx.Scope.Pop() // for symbol bindings.
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}
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// Statements
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func (e *evaluator) evalStatement(node ast.Statement) *unwind {
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@ -95,12 +107,8 @@ func (e *evaluator) evalStatement(node ast.Statement) *unwind {
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func (e *evaluator) evalBlock(node *ast.Block) *unwind {
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// Push a scope at the start, and pop it at afterwards; both for the symbol context and local variable values.
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e.ctx.Scope.Push()
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e.locals.Push()
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defer func() {
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e.locals.Pop()
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e.ctx.Scope.Pop()
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}()
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e.pushScope()
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defer e.popScope()
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for _, stmt := range node.Statements {
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if uw := e.evalStatement(stmt); uw != nil {
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@ -119,29 +127,12 @@ func (e *evaluator) evalLocalVariableDeclaration(node *ast.LocalVariableDeclarat
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// If there is a default value, set it now.
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if node.Local.Default != nil {
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obj := NewConstantObject(*node.Local.Default)
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contract.Assert(obj.Type == sym.Type())
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e.locals.Values[sym] = obj
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e.locals.SetValue(sym, obj)
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}
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return nil
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}
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func (e *evaluator) evalBreakStatement(node *ast.BreakStatement) *unwind {
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var label *tokens.Name
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if node.Label != nil {
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label = &node.Label.Ident
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}
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return breakUnwind(label)
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}
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func (e *evaluator) evalContinueStatement(node *ast.ContinueStatement) *unwind {
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var label *tokens.Name
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if node.Label != nil {
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label = &node.Label.Ident
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}
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return continueUnwind(label)
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}
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func (e *evaluator) evalTryCatchFinally(node *ast.TryCatchFinally) *unwind {
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// First, execute the TryBlock.
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uw := e.evalBlock(node.TryBlock)
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@ -149,13 +140,16 @@ func (e *evaluator) evalTryCatchFinally(node *ast.TryCatchFinally) *unwind {
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// The try block threw something; see if there is a handler that covers this.
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if node.CatchBlocks != nil {
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for _, catch := range *node.CatchBlocks {
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ex := e.ctx.RequireVariable(catch.Exception).Type()
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contract.Assert(types.CanConvert(ex, types.Error))
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if types.CanConvert(uw.Thrown.Type, ex) {
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// This type matched; set the exception type and swap the unwind information with the catch block's.
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// This has the effect of "handling" the exception (i.e., only reraise if the handler does).
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// TODO: set the value of the exception somehow.
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ex := e.ctx.RequireVariable(catch.Exception).(*symbols.LocalVariable)
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exty := ex.Type()
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contract.Assert(types.CanConvert(exty, types.Error))
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if types.CanConvert(uw.Thrown.Type, exty) {
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// This type matched, so this handler will catch the exception. Set the exception variable,
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// evaluate the block, and swap the unwind information (thereby "handling" the in-flight exception).
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e.pushScope()
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e.locals.SetValue(ex, uw.Thrown)
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uw = e.evalBlock(catch.Block)
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e.popScope()
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break
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}
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}
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@ -175,6 +169,22 @@ func (e *evaluator) evalTryCatchFinally(node *ast.TryCatchFinally) *unwind {
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return uw
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}
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func (e *evaluator) evalBreakStatement(node *ast.BreakStatement) *unwind {
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var label *tokens.Name
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if node.Label != nil {
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label = &node.Label.Ident
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}
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return breakUnwind(label)
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}
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func (e *evaluator) evalContinueStatement(node *ast.ContinueStatement) *unwind {
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var label *tokens.Name
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if node.Label != nil {
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label = &node.Label.Ident
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}
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return continueUnwind(label)
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}
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func (e *evaluator) evalIfStatement(node *ast.IfStatement) *unwind {
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// Evaluate the branches explicitly based on the result of the condition node.
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cond, uw := e.evalExpression(node.Condition)
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@ -4,32 +4,42 @@ package eval
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import (
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"github.com/marapongo/mu/pkg/compiler/symbols"
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"github.com/marapongo/mu/pkg/compiler/types"
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"github.com/marapongo/mu/pkg/util/contract"
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)
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// localScope is a kind of scope that holds local variable values.
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type localScope struct {
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Slot **localScope
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Parent *localScope
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Values ValueMap
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slot **localScope
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parent *localScope
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values valueMap
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}
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// valueMap maps local variables to their current known object value (if any).
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type valueMap map[*symbols.LocalVariable]*Object
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func initLocalScope(slot **localScope) *localScope {
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return &localScope{
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Slot: slot,
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Parent: *slot,
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Values: make(ValueMap),
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slot: slot,
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parent: *slot,
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values: make(valueMap),
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}
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}
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func (s *localScope) Push() *localScope {
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return initLocalScope(s.Slot)
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return initLocalScope(s.slot)
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}
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func (s *localScope) Pop() {
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contract.Assert(*s.Slot == s)
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*s.Slot = s.Parent
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contract.Assert(*s.slot == s)
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*s.slot = s.parent
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}
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// ValueMap maps local variables to their current known object value (if any).
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type ValueMap map[*symbols.LocalVariable]*Object
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func (s *localScope) GetValue(sym *symbols.LocalVariable) *Object {
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return s.values[sym]
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}
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func (s *localScope) SetValue(sym *symbols.LocalVariable, obj *Object) {
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contract.Assert(obj == nil || types.CanConvert(obj.Type, sym.Type()))
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s.values[sym] = obj
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}
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