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//==============================================================================
//
// Copyright (c) 2002-
// Authors:
// * Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
//
//------------------------------------------------------------------------------
//
// This file is part of PRISM.
//
// PRISM is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// PRISM is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with PRISM; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//==============================================================================
package parser.visitor;
import java.util.Vector;
import parser.ast.*;
import parser.type.*;
import prism.ModelType;
import prism.PrismLangException;
/**
* Perform any required semantic checks. Optionally pass in parent ModulesFile
* and PropertiesFile for some additional checks (or leave null);
*/
public class SemanticCheck extends ASTTraverse
{
private ModulesFile modulesFile;
private PropertiesFile propertiesFile;
// Sometimes we need to keep track of parent (ancestor) objects
private ModulesFile inModulesFile = null;
private Module inModule = null;
private Expression inInvariant = null;
private Expression inGuard = null;
private Update inUpdate = null;
public SemanticCheck()
{
this(null, null);
}
public SemanticCheck(ModulesFile modulesFile)
{
this(modulesFile, null);
}
public SemanticCheck(ModulesFile modulesFile, PropertiesFile propertiesFile)
{
setModulesFile(modulesFile);
setPropertiesFile(propertiesFile);
}
public void setModulesFile(ModulesFile modulesFile)
{
this.modulesFile = modulesFile;
}
public void setPropertiesFile(PropertiesFile propertiesFile)
{
this.propertiesFile = propertiesFile;
}
public void visitPre(ModulesFile e) throws PrismLangException
{
// Register the fact we are entering a model
inModulesFile = e;
}
public void visitPost(ModulesFile e) throws PrismLangException
{
int i, j, n, n2;
Module m;
Vector<String> v;
// Register the fact we are leaving a model
inModulesFile = null;
// Check for use of init...endinit _and_ var initial values
if (e.getInitialStates() != null) {
n = e.getNumGlobals();
for (i = 0; i < n; i++) {
if (e.getGlobal(i).isStartSpecified())
throw new PrismLangException("Cannot use both \"init...endinit\" and initial values for variables", e.getGlobal(i).getStart());
}
n = e.getNumModules();
for (i = 0; i < n; i++) {
m = e.getModule(i);
n2 = m.getNumDeclarations();
for (j = 0; j < n2; j++) {
if (m.getDeclaration(j).isStartSpecified())
throw new PrismLangException("Cannot use both \"init...endinit\" and initial values for variables", m.getDeclaration(j).getStart());
}
}
}
// Check system...endsystem construct (if present)
// Each module should appear exactly once
if (e.getSystemDefn() != null) {
e.getSystemDefn().getModules(v = new Vector<String>());
if (v.size() != e.getNumModules()) {
throw new PrismLangException("All modules must appear in the \"system\" construct exactly once", e.getSystemDefn());
}
n = e.getNumModules();
for (i = 0; i < n; i++) {
if (!(v.contains(e.getModuleName(i)))) {
throw new PrismLangException("All modules must appear in the \"system\" construct exactly once", e.getSystemDefn());
}
}
}
}
public Object visit(FormulaList e) throws PrismLangException
{
// Override - don't need to do any semantic checks on formulas
// (they will have been expanded in place, where needed)
// (and we shouldn't check them - e.g. clock vars appearing in errors would show as an error)
return null;
}
public void visitPost(LabelList e) throws PrismLangException
{
int i, n;
String s;
n = e.size();
for (i = 0; i < n; i++) {
s = e.getLabelName(i);
if ("deadlock".equals(s))
throw new PrismLangException("Cannot define a label called \"deadlock\" - this is a built-in label", e.getLabel(i));
if ("init".equals(s))
throw new PrismLangException("Cannot define a label called \"init\" - this is a built-in label", e.getLabel(i));
}
}
public void visitPost(ConstantList e) throws PrismLangException
{
int i, n;
n = e.size();
for (i = 0; i < n; i++) {
if (e.getConstant(i) != null && !e.getConstant(i).isConstant()) {
throw new PrismLangException("Definition of constant \"" + e.getConstantName(i) + "\" is not constant", e.getConstant(i));
}
}
}
public void visitPost(Declaration e) throws PrismLangException
{
if (e.getStart() != null && !e.getStart().isConstant()) {
throw new PrismLangException("Initial variable value of variable \"" + e.getName() + "\" is not constant", e.getStart());
}
// Clocks cannot be given initial variables
// (Note: it is safe to use getType() here because the type of a Declaration
// is set on construction, not during type checking).
if (e.getStart() != null && e.getType() instanceof TypeClock) {
throw new PrismLangException("Cannot specify initial value for a clock", e);
}
}
public void visitPost(DeclarationInt e) throws PrismLangException
{
if (e.getLow() != null && !e.getLow().isConstant()) {
throw new PrismLangException("Integer range lower bound \"" + e.getLow() + "\" is not constant", e.getLow());
}
if (e.getHigh() != null && !e.getHigh().isConstant()) {
throw new PrismLangException("Integer range upper bound \"" + e.getLow() + "\" is not constant", e.getLow());
}
}
public void visitPost(DeclarationArray e) throws PrismLangException
{
if (e.getLow() != null && !e.getLow().isConstant()) {
throw new PrismLangException("Array lower bound \"" + e.getLow() + "\" is not constant", e.getLow());
}
if (e.getHigh() != null && !e.getHigh().isConstant()) {
throw new PrismLangException("Array upper bound \"" + e.getLow() + "\" is not constant", e.getLow());
}
}
public void visitPost(DeclarationClock e) throws PrismLangException
{
// Clocks are only allowed in PTA models
if (modulesFile.getModelType() != ModelType.PTA) {
throw new PrismLangException("Clock variables are only allowed in PTA models", e);
}
}
public void visitPre(Module e) throws PrismLangException
{
// Register the fact we are entering a module
inModule = e;
}
public Object visit(Module e) throws PrismLangException
{
// Override this so we can keep track of when we are in an invariant
visitPre(e);
int i, n;
n = e.getNumDeclarations();
for (i = 0; i < n; i++) {
if (e.getDeclaration(i) != null) e.getDeclaration(i).accept(this);
}
inInvariant = e.getInvariant();
if (e.getInvariant() != null)
e.getInvariant().accept(this);
inInvariant = null;
n = e.getNumCommands();
for (i = 0; i < n; i++) {
if (e.getCommand(i) != null) e.getCommand(i).accept(this);
}
visitPost(e);
return null;
}
public void visitPost(Module e) throws PrismLangException
{
// Register the fact we are leaving a module
inModule = null;
}
public Object visit(Command e) throws PrismLangException
{
// Override this so we can keep track of when we are in a command
visitPre(e);
inGuard = e.getGuard();
e.getGuard().accept(this);
inGuard = null;
e.getUpdates().accept(this);
visitPost(e);
return null;
}
public void visitPre(Update e) throws PrismLangException
{
// Register the fact we are entering an update
inUpdate = e;
}
public void visitPost(Update e) throws PrismLangException
{
int i, n;
String s, var;
Command c;
Module m;
ModulesFile mf;
boolean isLocal, isGlobal;
// Register the fact we are leaving an update
inUpdate = null;
// Determine containing command/module/model
// (mf should coincide with the stored modulesFile)
c = e.getParent().getParent();
m = c.getParent();
mf = m.getParent();
n = e.getNumElements();
for (i = 0; i < n; i++) {
// Check that the update is allowed to modify this variable
var = e.getVar(i);
isLocal = m.isLocalVariable(var);
isGlobal = isLocal ? false : mf.isGlobalVariable(var);
if (!isLocal && !isGlobal) {
s = "Module \"" + m.getName() + "\" is not allowed to modify variable \"" + var + "\"";
throw new PrismLangException(s, e.getVarIdent(i));
}
if (isGlobal && !c.getSynch().equals("")) {
s = "Synchronous command cannot modify global variable";
throw new PrismLangException(s, e.getVarIdent(i));
}
}
}
public void visitPost(SystemRename e) throws PrismLangException
{
int i, n;
String s;
Vector<String> v;
// Check all actions are valid and ensure no duplicates
// (only check "from": OK to introduce new actions and to map to same
// action)
v = new Vector<String>();
n = e.getNumRenames();
for (i = 0; i < n; i++) {
s = e.getFrom(i);
if (!modulesFile.isSynch(s)) {
throw new PrismLangException("Invalid action \"" + s + "\" in \"system\" construct", e);
}
if (v.contains(s)) {
throw new PrismLangException("Duplicated action \"" + s + "\" in parallel composition in \"system\" construct", e);
} else {
v.addElement(s);
}
}
}
public void visitPost(SystemHide e) throws PrismLangException
{
int i, n;
String s;
Vector<String> v;
// Check all actions are valid and ensure no duplicates
v = new Vector<String>();
n = e.getNumActions();
for (i = 0; i < n; i++) {
s = e.getAction(i);
if (!modulesFile.isSynch(s)) {
throw new PrismLangException("Invalid action \"" + s + "\" in \"system\" construct", e);
}
if (v.contains(s)) {
throw new PrismLangException("Duplicated action \"" + s + "\" in parallel composition in \"system\" construct", e);
} else {
v.addElement(s);
}
}
}
public void visitPost(SystemParallel e) throws PrismLangException
{
int i, n;
String s;
Vector<String> v;
// Check all actions are valid and ensure no duplicates
v = new Vector<String>();
n = e.getNumActions();
for (i = 0; i < n; i++) {
s = e.getAction(i);
if (!modulesFile.isSynch(s)) {
throw new PrismLangException("Invalid action \"" + s + "\" in \"system\" construct", e);
}
if (v.contains(s)) {
throw new PrismLangException("Duplicated action \"" + s + "\" in parallel composition in \"system\" construct", e);
} else {
v.addElement(s);
}
}
}
public void visitPost(ExpressionTemporal e) throws PrismLangException
{
int op = e.getOperator();
Expression operand1 = e.getOperand1();
Expression operand2 = e.getOperand2();
Expression lBound = e.getLowerBound();
Expression uBound = e.getUpperBound();
if (lBound != null && !lBound.isConstant()) {
throw new PrismLangException("Lower bound in " + e.getOperatorSymbol() + " operator is not constant", lBound);
}
if (uBound != null && !uBound.isConstant()) {
throw new PrismLangException("Upper bound in " + e.getOperatorSymbol() + " operator is not constant", uBound);
}
// Other checks (which parser should never allow to occur anyway)
if (op == ExpressionTemporal.P_X && (operand1 != null || operand2 == null || lBound != null || uBound != null)) {
throw new PrismLangException("Cannot attach bounds to " + e.getOperatorSymbol() + " operator", e);
}
if (op == ExpressionTemporal.R_C && (operand1 != null || operand2 != null || lBound != null || uBound == null)) {
throw new PrismLangException("Badly formed " + e.getOperatorSymbol() + " operator", e);
}
if (op == ExpressionTemporal.R_I && (operand1 != null || operand2 != null || lBound != null || uBound == null)) {
throw new PrismLangException("Badly formed " + e.getOperatorSymbol() + " operator", e);
}
if (op == ExpressionTemporal.R_F && (operand1 != null || operand2 == null || lBound != null || uBound != null)) {
throw new PrismLangException("Badly formed " + e.getOperatorSymbol() + " operator", e);
}
if (op == ExpressionTemporal.R_S && (operand1 != null || operand2 != null || lBound != null || uBound != null)) {
throw new PrismLangException("Badly formed " + e.getOperatorSymbol() + " operator", e);
}
}
public void visitPost(ExpressionFunc e) throws PrismLangException
{
// Check function name is valid
if (e.getNameCode() == -1) {
throw new PrismLangException("Unknown function \"" + e.getName() + "\"", e);
}
// Check num arguments
if (e.getNumOperands() < e.getMinArity()) {
throw new PrismLangException("Not enough arguments to \"" + e.getName() + "\" function", e);
}
if (e.getMaxArity() != -1 && e.getNumOperands() > e.getMaxArity()) {
throw new PrismLangException("Too many " + e.getMaxArity() + "arguments to \"" + e.getName() + "\" function", e);
}
}
public void visitPost(ExpressionIdent e) throws PrismLangException
{
// By the time the expression is checked, this should
// have been converted to an ExpressionVar/ExpressionConstant/...
throw new PrismLangException("Undeclared identifier", e);
}
public void visitPost(ExpressionFormula e) throws PrismLangException
{
// This should have been defined or expanded by now
if (e.getDefinition() == null)
throw new PrismLangException("Unexpanded formula", e);
}
public void visitPost(ExpressionVar e) throws PrismLangException
{
// For PTAs, references to variables in modules have to be local
// (no longer checked here, e.g. because allowed for digital clocks)
/*if (modulesFile != null && modulesFile.getModelType() == ModelType.PTA && inModule != null) {
if (!inModule.isLocalVariable(e.getName())) {
throw new PrismLangException("Modules in a PTA cannot access non-local variables", e);
}
}*/
// Clock references, in models, can only appear in invariants and guards
// (Note: type checking has not been done, but we know types for ExpressionVars)
if (e.getType() instanceof TypeClock && inModulesFile != null) {
if (inInvariant == null && inGuard == null) {
throw new PrismLangException("Reference to a clock variable cannot appear here", e);
}
}
}
public void visitPost(ExpressionProb e) throws PrismLangException
{
if (e.getProb() != null && !e.getProb().isConstant()) {
throw new PrismLangException("P operator probability bound is not constant", e.getProb());
}
}
public void visitPost(ExpressionReward e) throws PrismLangException
{
if (e.getRewardStructIndex() != null) {
if (e.getRewardStructIndex() instanceof Expression) {
Expression rsi = (Expression) e.getRewardStructIndex();
if (!(rsi.isConstant())) {
throw new PrismLangException("R operator reward struct index is not constant", rsi);
}
} else if (e.getRewardStructIndex() instanceof String) {
String s = (String) e.getRewardStructIndex();
if (modulesFile != null && modulesFile.getRewardStructIndex(s) == -1) {
throw new PrismLangException("R operator reward struct index \"" + s + "\" does not exist", e);
}
}
}
if (e.getReward() != null && !e.getReward().isConstant()) {
throw new PrismLangException("R operator reward bound is not constant", e.getReward());
}
}
public void visitPost(ExpressionSS e) throws PrismLangException
{
if (e.getProb() != null && !e.getProb().isConstant()) {
throw new PrismLangException("S operator probability bound is not constant", e.getProb());
}
}
public void visitPost(ExpressionLabel e) throws PrismLangException
{
LabelList labelList;
if (propertiesFile != null)
labelList = propertiesFile.getCombinedLabelList();
else if (modulesFile != null)
labelList = modulesFile.getLabelList();
else
throw new PrismLangException("Undeclared label", e);
String name = e.getName();
// Allow special cases
if ("deadlock".equals(name) || "init".equals(name))
return;
// Otherwise check list
if (labelList == null || labelList.getLabelIndex(name) == -1) {
throw new PrismLangException("Undeclared label", e);
}
}
public void visitPost(ExpressionFilter e) throws PrismLangException
{
// Check filter type is valid
if (e.getOperatorType() == null) {
throw new PrismLangException("Unknown filter type \"" + e.getOperatorName() + "\"", e);
}
}
}