Merge pull request #42914 from Shadow-Devil/stack-to-deque

[Refactoring] Replace "Stack" with "Deque".

ballerina-shell/modules/shell-cli/src/main/java/io/ballerina/shell/cli/jline/parser/ParserStateMachine.java

@@ -18,9 +18,10 @@
 
 package io.ballerina.shell.cli.jline.parser;
 
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.Map;
 import java.util.Set;
-import java.util.Stack;
 
 /**
  * State machine implementation for ballerina parser.
@@ -65,12 +66,12 @@ public class ParserStateMachine {
                     CLOSE_PAREN, OPEN_PAREN,
                     CLOSE_SQ_BR, OPEN_SQ_BR);
 
-    private final Stack<Character> stack;
+    private final Deque<Character> stack;
     private ParserState state;
 
     public ParserStateMachine() {
         this.state = ParserState.NORMAL;
-        this.stack = new Stack<>();
+        this.stack = new ArrayDeque<>();
     }
 
     public void feed(char character) {
@@ -138,9 +139,9 @@ private void normalStateOrAfterOperator(char character) {
             case CLOSE_CURLY:
             case CLOSE_PAREN:
             case CLOSE_SQ_BR:
-                if (!stack.empty() && OPEN_BRACKETS.get(character).equals(stack.peek())) {
+                if (!stack.isEmpty() && OPEN_BRACKETS.get(character).equals(stack.peek())) {
                     stack.pop();
-                    if (!stack.empty() && stack.peek() == BACKTICK) {
+                    if (!stack.isEmpty() && stack.peek() == BACKTICK) {
                         state = ParserState.IN_TEMPLATE;
                     }
                     break;
@@ -238,7 +239,7 @@ private void inTemplateState(char character) {
                 state = ParserState.IN_TEMPLATE_AFTER_DOLLAR;
                 break;
             case BACKTICK:
-                if (!stack.empty() && stack.peek() == BACKTICK) {
+                if (!stack.isEmpty() && stack.peek() == BACKTICK) {
                     state = ParserState.NORMAL;
                     stack.pop();
                     break;
@@ -310,6 +311,6 @@ public boolean isIncomplete() {
             return true;
         }
         // Otherwise, all brackets/backticks are closed is completion
-        return !stack.empty();
+        return !stack.isEmpty();
     }
 }

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/preprocessor/SeparatorPreprocessor.java

@@ -20,10 +20,11 @@
 
 import io.ballerina.shell.exceptions.PreprocessorException;
 
+import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Deque;
 import java.util.List;
-import java.util.Stack;
 
 /**
  * Preprocessor to split the input into several statements
@@ -51,7 +52,7 @@ public Collection<String> process(String input) throws PreprocessorException {
         List<String> snippets = new ArrayList<>();
         StringBuilder builder = new StringBuilder();
 
-        Stack<Character> brackets = new Stack<>();
+        Deque<Character> brackets = new ArrayDeque<>();
 
         boolean isInBacktickLiteral = false;
         boolean isInQuoteLiteral = false;

bvm/ballerina-runtime/src/main/java/io/ballerina/runtime/internal/scheduling/ItemGroup.java

@@ -18,7 +18,8 @@
 
 package io.ballerina.runtime.internal.scheduling;
 
-import java.util.Stack;
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.locks.ReentrantLock;
@@ -38,7 +39,7 @@ public class ItemGroup {
      * Keep the list of items that should run on same thread.
      * Using a stack to get advantage of the locality.
      */
-    Stack<SchedulerItem> items = new Stack<>();
+    Deque<SchedulerItem> items = new ArrayDeque<>();
 
     /**
      * Indicates this item is already in runnable list/executing or not.

bvm/ballerina-runtime/src/main/java/io/ballerina/runtime/internal/scheduling/RuntimeRegistry.java

@@ -26,10 +26,11 @@
 import io.ballerina.runtime.internal.values.FutureValue;
 
 import java.io.PrintStream;
+import java.util.Deque;
 import java.util.Iterator;
 import java.util.Set;
-import java.util.Stack;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedDeque;
 import java.util.function.Function;
 
 import static io.ballerina.runtime.api.values.BError.ERROR_PRINT_PREFIX;
@@ -43,7 +44,7 @@ public class RuntimeRegistry {
 
     private final Scheduler scheduler;
     private final Set<BObject> listenerSet = ConcurrentHashMap.newKeySet();
-    private final Stack<BFunctionPointer<?, ?>> stopHandlerStack = new Stack<>();
+    private final Deque<BFunctionPointer<?, ?>> stopHandlerStack = new ConcurrentLinkedDeque<>();
 
     private static final PrintStream outStream = System.err;
 

bvm/ballerina-runtime/src/main/java/io/ballerina/runtime/internal/scheduling/Scheduler.java

@@ -335,7 +335,7 @@ private void run() {
                 }
                 postProcess(item, result, panic);
                 group.lock();
-                if ((isItemsEmpty = group.items.empty())) {
+                if ((isItemsEmpty = group.items.isEmpty())) {
                     group.scheduled.set(false);
                 }
                 group.unlock();

bvm/ballerina-runtime/src/main/java/io/ballerina/runtime/transactions/TransactionLocalContext.java

@@ -22,9 +22,10 @@
 import io.ballerina.runtime.internal.scheduling.Strand;
 
 import java.nio.ByteBuffer;
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Stack;
 
 /**
  * {@code TransactionLocalContext} stores the transaction related information.
@@ -41,8 +42,8 @@ public class TransactionLocalContext {
     private Map<String, Integer> allowedTransactionRetryCounts;
     private Map<String, Integer> currentTransactionRetryCounts;
     private Map<String, BallerinaTransactionContext> transactionContextStore;
-    private Stack<String> transactionBlockIdStack;
-    private Stack<TransactionFailure> transactionFailure;
+    private Deque<String> transactionBlockIdStack;
+    private Deque<TransactionFailure> transactionFailure;
     private static final TransactionResourceManager transactionResourceManager =
             TransactionResourceManager.getInstance();
     private boolean isResourceParticipant;
@@ -59,8 +60,8 @@ private TransactionLocalContext(String globalTransactionId, String url, String p
         this.allowedTransactionRetryCounts = new HashMap<>();
         this.currentTransactionRetryCounts = new HashMap<>();
         this.transactionContextStore = new HashMap<>();
-        this.transactionBlockIdStack = new Stack<>();
-        this.transactionFailure = new Stack<>();
+        this.transactionBlockIdStack = new ArrayDeque<>();
+        this.transactionFailure = new ArrayDeque<>();
         this.rollbackOnlyError = null;
         this.isTransactional = true;
         this.transactionId = ValueCreator.createArrayValue(globalTransactionId.getBytes());
@@ -104,7 +105,7 @@ public void addCurrentTransactionBlockId(String blockId) {
     }
 
     public boolean hasTransactionBlock() {
-        return !transactionBlockIdStack.empty();
+        return !transactionBlockIdStack.isEmpty();
     }
 
     public String getURL() {
@@ -211,7 +212,7 @@ public void markFailure() {
     }
 
     public TransactionFailure getAndClearFailure() {
-        if (transactionFailure.empty()) {
+        if (transactionFailure.isEmpty()) {
             return null;
         }
         TransactionFailure failure = transactionFailure.pop();
@@ -220,7 +221,7 @@ public TransactionFailure getAndClearFailure() {
     }
 
     public TransactionFailure getFailure() {
-        if (transactionFailure.empty()) {
+        if (transactionFailure.isEmpty()) {
             return null;
         }
         return transactionFailure.peek();

compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/bir/BIRGenEnv.java

@@ -28,10 +28,11 @@
 import org.wso2.ballerinalang.compiler.util.Name;
 import org.wso2.ballerinalang.compiler.util.Names;
 
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Stack;
 
 /**
  * Stores the state such as the current node, enclosing package, function etc, during bir generation.
@@ -59,15 +60,15 @@ class BIRGenEnv {
     BIRBasicBlock enclOnFailEndBB;
     BIRBasicBlock enclInnerOnFailEndBB;
 
-    Stack<List<BIRBasicBlock>> trapBlocks = new Stack<>();
+    Deque<List<BIRBasicBlock>> trapBlocks = new ArrayDeque<>();
 
     Map<BlockNode, List<BIRVariableDcl>> varDclsByBlock = new HashMap<>();
 
     // This is to hold variables to unlock in each scope
     // for example when we are to return from somewhere, we need to unlock all the
     // values in this list, but if we are to do break or continue, we need to pop
     // list and unlock variables in that
-    Stack<BIRLockDetailsHolder> unlockVars = new Stack<>();
+    Deque<BIRLockDetailsHolder> unlockVars = new ArrayDeque<>();
 
     // This is the basic block that contains the return instruction for the current function.
     // A function can have only one basic block that has a return instruction.

compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/desugar/Desugar.java

@@ -307,10 +307,12 @@
 import org.wso2.ballerinalang.util.Flags;
 import org.wso2.ballerinalang.util.Lists;
 
+import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.Deque;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -321,7 +323,6 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
-import java.util.Stack;
 import java.util.TreeMap;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -397,7 +398,7 @@ public class Desugar extends BLangNodeVisitor {
     private ClassClosureDesugar classClosureDesugar;
     private LargeMethodSplitter largeMethodSplitter;
 
-    public Stack<BLangLockStmt> enclLocks = new Stack<>();
+    public Deque<BLangLockStmt> enclLocks = new ArrayDeque<>();
     private BLangOnFailClause onFailClause;
     private boolean shouldReturnErrors;
     private int transactionBlockCount;
@@ -423,8 +424,8 @@ public class Desugar extends BLangNodeVisitor {
     private Set<BLangWorkerSendReceiveExpr.Channel> channelsWithinIfStmt = new LinkedHashSet<>();
 
     // Safe navigation related variables
-    private Stack<BLangMatchStatement> matchStmtStack = new Stack<>();
-    Stack<BLangExpression> accessExprStack = new Stack<>();
+    private Deque<BLangMatchStatement> matchStmtStack = new ArrayDeque<>();
+    Deque<BLangExpression> accessExprStack = new ArrayDeque<>();
     private BLangMatchClause successClause;
     private BLangAssignment safeNavigationAssignment;
     static boolean isJvmTarget = false;
@@ -10075,13 +10076,13 @@ private BLangExpression rewriteSafeNavigationExpr(BLangAccessExpression accessEx
         handleSafeNavigation(blockStmt, accessExpr, accessExpr.getBType(), tempResultVar);
 
         // Create a statement-expression including the match statement
-        BLangMatchStatement matchStmt = this.matchStmtStack.firstElement();
+        BLangMatchStatement matchStmt = this.matchStmtStack.getLast();
         blockStmt.stmts.add(matchStmt);
         BLangStatementExpression stmtExpression = createStatementExpression(blockStmt, tempResultVarRef);
         stmtExpression.setBType(originalExprType);
         // Reset the variables
-        this.matchStmtStack = new Stack<>();
-        this.accessExprStack = new Stack<>();
+        this.matchStmtStack = new ArrayDeque<>();
+        this.accessExprStack = new ArrayDeque<>();
         this.successClause = null;
         this.safeNavigationAssignment = null;
         return stmtExpression;

compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/parser/BLangAnonymousModelHelper.java

@@ -21,10 +21,10 @@
 import org.wso2.ballerinalang.compiler.util.CompilerContext;
 import org.wso2.ballerinalang.compiler.util.Name;
 
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
-import java.util.Stack;
 
 import static io.ballerina.runtime.api.constants.RuntimeConstants.UNDERSCORE;
 
@@ -101,17 +101,17 @@ public String getNextAnonymousTypeKey(PackageID packageID) {
         return ANON_TYPE + UNDERSCORE + nextValue;
     }
 
-    public String getNextAnonymousTypeKey(PackageID packageID, Stack<String> suffixes) {
+    public String getNextAnonymousTypeKey(PackageID packageID, Collection<String> suffixes) {
         if (suffixes.isEmpty()) {
             return getNextAnonymousTypeKey(packageID);
         }
         return createAnonTypeName(suffixes, packageID);
     }
 
-    private String createAnonTypeName(Stack<String> suffixes, PackageID pkgId) {
+    private String createAnonTypeName(Collection<String> suffixes, PackageID pkgId) {
         StringBuilder name = new StringBuilder(ANON_TYPE);
-        for (int i = suffixes.size() - 1; i >= 0; i--) {
-            name.append(suffixes.elementAt(i)).append(DOLLAR);
+        for (String suffix : suffixes) {
+            name.append(suffix).append(DOLLAR);
         }
         Map<String, Integer> anonTypesNames = anonTypesNamesPerPkg.computeIfAbsent(pkgId, key -> new HashMap<>());
         String nameStr = name.toString();

compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/parser/BLangNodeBuilder.java

@@ -500,15 +500,16 @@
 import org.wso2.ballerinalang.compiler.util.QuoteType;
 import org.wso2.ballerinalang.compiler.util.TypeTags;
 
+import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Deque;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
-import java.util.Stack;
 import java.util.regex.Matcher;
 
 import static org.ballerinalang.model.elements.Flag.INCLUDED;
@@ -539,8 +540,8 @@ public class BLangNodeBuilder extends NodeTransformer<BLangNode> {
     private BLangMissingNodesHelper missingNodesHelper;
 
     /* To keep track of additional statements produced from multi-BLangNode resultant transformations */
-    private Stack<BLangStatement> additionalStatements = new Stack<>();
-    private final Stack<String> anonTypeNameSuffixes = new Stack<>();
+    private Deque<BLangStatement> additionalStatements = new ArrayDeque<>();
+    private final Deque<String> anonTypeNameSuffixes = new ArrayDeque<>();
     /* To keep track if we are inside a block statment for the use of type definition creation */
     private boolean isInLocalContext = false;
     /* To keep track if we are inside a finite context */
@@ -566,7 +567,7 @@ public List<org.ballerinalang.model.tree.Node> accept(Node node) {
         BLangNode bLangNode = node.apply(this);
         List<org.ballerinalang.model.tree.Node> nodes = new ArrayList<>();
         // if not already consumed, add left-over statements
-        while (!additionalStatements.empty()) {
+        while (!additionalStatements.isEmpty()) {
             nodes.add(additionalStatements.pop());
         }
         nodes.add(bLangNode);
@@ -1681,7 +1682,7 @@ public BLangNode transform(FunctionBodyBlockNode functionBodyBlockNode) {
             for (NamedWorkerDeclarationNode workerDeclarationNode : namedWorkerDeclarator.namedWorkerDeclarations()) {
                 stmtList.add((BLangStatement) workerDeclarationNode.apply(this));
                 // Consume resultant additional statements
-                while (!this.additionalStatements.empty()) {
+                while (!this.additionalStatements.isEmpty()) {
                     stmtList.add(additionalStatements.pop());
                 }
             }
@@ -5433,7 +5434,7 @@ private void generateForkStatements(List<BLangStatement> statements, ForkStateme
             function.anonForkName = nextAnonymousForkKey;
 
             statements.add(workerDef);
-            while (!this.additionalStatements.empty()) {
+            while (!this.additionalStatements.isEmpty()) {
                 statements.add(additionalStatements.pop());
             }
             forkJoin.addWorkers(workerDef);