Урок 8. break, continue, цикл do/while

program.txt

@@ -13,10 +13,18 @@ if (40 < 50 || 50 > 60) {
     print "true1\n"
     print "true2\n"
     i = 0
+    print "do while"
+    do {
+       print "i = " + i + "\n"
+       i = i + 1
+    } while (i < 10)
+    i = 0
+    print "while"
     while (i < 10) {
         print "i = " + i + "\n"
         i = i + 1
     }
+    print "for"
     for i = 0, i < 10, i = i + 1 {
         print "i = " + i + "\n"
     }

src/com/annimon/ownlang/parser/Lexer.java

@@ -150,6 +150,9 @@ public final class Lexer {
             case "else": addToken(TokenType.ELSE); break;
             case "while": addToken(TokenType.WHILE); break;
             case "for": addToken(TokenType.FOR); break;
+            case "do": addToken(TokenType.DO); break;
+            case "break": addToken(TokenType.BREAK); break;
+            case "continue": addToken(TokenType.CONTINUE); break;
             default:
                 addToken(TokenType.WORD, word);
                 break;

src/com/annimon/ownlang/parser/Parser.java

@@ -1,19 +1,6 @@
 package com.annimon.ownlang.parser;
 
-import com.annimon.ownlang.parser.ast.PrintStatement;
-import com.annimon.ownlang.parser.ast.AssignmentStatement;
-import com.annimon.ownlang.parser.ast.BinaryExpression;
-import com.annimon.ownlang.parser.ast.BlockStatement;
-import com.annimon.ownlang.parser.ast.ConditionalExpression;
-import com.annimon.ownlang.parser.ast.VariableExpression;
-import com.annimon.ownlang.parser.ast.Expression;
-import com.annimon.ownlang.parser.ast.ForStatement;
-import com.annimon.ownlang.parser.ast.IfStatement;
-import com.annimon.ownlang.parser.ast.ValueExpression;
-import com.annimon.ownlang.parser.ast.Statement;
-import com.annimon.ownlang.parser.ast.UnaryExpression;
-import com.annimon.ownlang.parser.ast.WhileStatement;
-import java.util.ArrayList;
+import com.annimon.ownlang.parser.ast.*;
 import java.util.List;
 
 /**
@@ -66,6 +53,15 @@ public final class Parser {
         if (match(TokenType.WHILE)) {
             return whileStatement();
         }
+        if (match(TokenType.DO)) {
+            return doWhileStatement();
+        }
+        if (match(TokenType.BREAK)) {
+            return new BreakStatement();
+        }
+        if (match(TokenType.CONTINUE)) {
+            return new ContinueStatement();
+        }
         if (match(TokenType.FOR)) {
             return forStatement();
         }
@@ -101,6 +97,13 @@ public final class Parser {
         return new WhileStatement(condition, statement);
     }
     
+    private Statement doWhileStatement() {
+        final Statement statement = statementOrBlock();
+        consume(TokenType.WHILE);
+        final Expression condition = expression();
+        return new DoWhileStatement(condition, statement);
+    }
+    
     private Statement forStatement() {
         final Statement initialization = assignmentStatement();
         consume(TokenType.COMMA);

src/com/annimon/ownlang/parser/TokenType.java

@@ -17,6 +17,9 @@ public enum TokenType {
     ELSE,
     WHILE,
     FOR,
+    DO,
+    BREAK,
+    CONTINUE,
     
     PLUS,
     MINUS,

src/com/annimon/ownlang/parser/ast/BreakStatement.java

@@ -0,0 +1,18 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class BreakStatement extends RuntimeException implements Statement {
+
+    @Override
+    public void execute() {
+        throw this;
+    }
+
+    @Override
+    public String toString() {
+        return "break";
+    }
+}

src/com/annimon/ownlang/parser/ast/ContinueStatement.java

@@ -0,0 +1,18 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class ContinueStatement extends RuntimeException implements Statement {
+
+    @Override
+    public void execute() {
+        throw this;
+    }
+
+    @Override
+    public String toString() {
+        return "continue";
+    }
+}

src/com/annimon/ownlang/parser/ast/DoWhileStatement.java

@@ -0,0 +1,35 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class DoWhileStatement implements Statement {
+    
+    private final Expression condition;
+    private final Statement statement;
+
+    public DoWhileStatement(Expression condition, Statement statement) {
+        this.condition = condition;
+        this.statement = statement;
+    }
+    
+    @Override
+    public void execute() {
+        do {
+            try {
+                statement.execute();
+            } catch (BreakStatement bs) {
+                break;
+            } catch (ContinueStatement cs) {
+                // continue;
+            }
+        }
+        while (condition.eval().asNumber() != 0);
+    }
+
+    @Override
+    public String toString() {
+        return "do " + statement + " while " + condition;
+    }
+}

src/com/annimon/ownlang/parser/ast/ForStatement.java

@@ -21,7 +21,13 @@ public final class ForStatement implements Statement {
     @Override
     public void execute() {
         for (initialization.execute(); termination.eval().asNumber() != 0; increment.execute()) {
-            statement.execute();
+            try {
+                statement.execute();
+            } catch (BreakStatement bs) {
+                break;
+            } catch (ContinueStatement cs) {
+                // continue;
+            }
         }
     }
 

src/com/annimon/ownlang/parser/ast/WhileStatement.java

@@ -17,7 +17,13 @@ public final class WhileStatement implements Statement {
     @Override
     public void execute() {
         while (condition.eval().asNumber() != 0) {
-            statement.execute();
+            try {
+                statement.execute();
+            } catch (BreakStatement bs) {
+                break;
+            } catch (ContinueStatement cs) {
+                // continue;
+            }
         }
     }