Урок 7. Блок операторов, циклы

program.txt

@@ -9,5 +9,16 @@ print "\n"
 if (1 <= 2) print "1 = 1"
 else print "1 != 1"
 print "\n"
-if (40 < 50 && 50 > 60) print "true"
+if (40 < 50 || 50 > 60) {
+    print "true1\n"
+    print "true2\n"
+    i = 0
+    while (i < 10) {
+        print "i = " + i + "\n"
+        i = i + 1
+    }
+    for i = 0, i < 10, i = i + 1 {
+        print "i = " + i + "\n"
+    }
+}
 else print "false"

src/com/annimon/ownlang/Main.java

@@ -22,12 +22,8 @@ public final class Main {
             System.out.println(token);
         }
         
-        final List<Statement> statements = new Parser(tokens).parse();
-        for (Statement statement : statements) {
-            System.out.println(statement);
-        }
-        for (Statement statement : statements) {
-            statement.execute();
-        }
+        final Statement program = new Parser(tokens).parse();
+        System.out.println(program.toString());
+        program.execute();
     }
 }

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

@@ -11,7 +11,7 @@ import java.util.Map;
  */
 public final class Lexer {
     
-    private static final String OPERATOR_CHARS = "+-*/()=<>!&|";
+    private static final String OPERATOR_CHARS = "+-*/(){}=<>!&|,";
     
     private static final Map<String, TokenType> OPERATORS;
     static {
@@ -22,9 +22,12 @@ public final class Lexer {
         OPERATORS.put("/", TokenType.SLASH);
         OPERATORS.put("(", TokenType.LPAREN);
         OPERATORS.put(")", TokenType.RPAREN);
+        OPERATORS.put("{", TokenType.LBRACE);
+        OPERATORS.put("}", TokenType.RBRACE);
         OPERATORS.put("=", TokenType.EQ);
         OPERATORS.put("<", TokenType.LT);
         OPERATORS.put(">", TokenType.GT);
+        OPERATORS.put(",", TokenType.COMMA);
         
         OPERATORS.put("!", TokenType.EXCL);
         OPERATORS.put("&", TokenType.AMP);
@@ -145,6 +148,8 @@ public final class Lexer {
             case "print": addToken(TokenType.PRINT); break;
             case "if": addToken(TokenType.IF); break;
             case "else": addToken(TokenType.ELSE); break;
+            case "while": addToken(TokenType.WHILE); break;
+            case "for": addToken(TokenType.FOR); break;
             default:
                 addToken(TokenType.WORD, word);
                 break;

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

@@ -3,13 +3,16 @@ 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.VariabletExpression;
 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 java.util.List;
 
@@ -31,14 +34,28 @@ public final class Parser {
         size = tokens.size();
     }
     
-    public List<Statement> parse() {
-        final List<Statement> result = new ArrayList<>();
+    public Statement parse() {
+        final BlockStatement result = new BlockStatement();
         while (!match(TokenType.EOF)) {
             result.add(statement());
         }
         return result;
     }
     
+    private Statement block() {
+        final BlockStatement block = new BlockStatement();
+        consume(TokenType.LBRACE);
+        while (!match(TokenType.RBRACE)) {
+            block.add(statement());
+        }
+        return block;
+    }
+    
+    private Statement statementOrBlock() {
+        if (get(0).getType() == TokenType.LBRACE) return block();
+        return statement();
+    }
+    
     private Statement statement() {
         if (match(TokenType.PRINT)) {
             return new PrintStatement(expression());
@@ -46,6 +63,12 @@ public final class Parser {
         if (match(TokenType.IF)) {
             return ifElse();
         }
+        if (match(TokenType.WHILE)) {
+            return whileStatement();
+        }
+        if (match(TokenType.FOR)) {
+            return forStatement();
+        }
         return assignmentStatement();
     }
     
@@ -62,16 +85,32 @@ public final class Parser {
     
     private Statement ifElse() {
         final Expression condition = expression();
-        final Statement ifStatement = statement();
+        final Statement ifStatement = statementOrBlock();
         final Statement elseStatement;
         if (match(TokenType.ELSE)) {
-            elseStatement = statement();
+            elseStatement = statementOrBlock();
         } else {
             elseStatement = null;
         }
          return new IfStatement(condition, ifStatement, elseStatement);
     }
     
+    private Statement whileStatement() {
+        final Expression condition = expression();
+        final Statement statement = statementOrBlock();
+        return new WhileStatement(condition, statement);
+    }
+    
+    private Statement forStatement() {
+        final Statement initialization = assignmentStatement();
+        consume(TokenType.COMMA);
+        final Expression termination = expression();
+        consume(TokenType.COMMA);
+        final Statement increment = assignmentStatement();
+        final Statement statement = statementOrBlock();
+        return new ForStatement(initialization, termination, increment, statement);
+    }
+    
     
     private Expression expression() {
         return logicalOr();

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

@@ -15,6 +15,8 @@ public enum TokenType {
     PRINT,
     IF,
     ELSE,
+    WHILE,
+    FOR,
     
     PLUS,
     MINUS,
@@ -36,6 +38,9 @@ public enum TokenType {
     
     LPAREN, // (
     RPAREN, // )
+    LBRACE, // {
+    RBRACE, // }
+    COMMA, // ,
     
     EOF
 }

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

@@ -0,0 +1,37 @@
+package com.annimon.ownlang.parser.ast;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class BlockStatement implements Statement {
+    
+    private final List<Statement> statements;
+
+    public BlockStatement() {
+        statements = new ArrayList<>();
+    }
+    
+    public void add(Statement statement) {
+        statements.add(statement);
+    }
+
+    @Override
+    public void execute() {
+        for (Statement statement : statements) {
+            statement.execute();
+        }
+    }
+
+    @Override
+    public String toString() {
+        final StringBuilder result = new StringBuilder();
+        for (Statement statement : statements) {
+            result.append(statement.toString()).append(System.lineSeparator());
+        }
+        return result.toString();
+    }
+}

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

@@ -0,0 +1,32 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class ForStatement implements Statement {
+    
+    private final Statement initialization;
+    private final Expression termination;
+    private final Statement increment;
+    private final Statement statement;
+
+    public ForStatement(Statement initialization, Expression termination, Statement increment, Statement block) {
+        this.initialization = initialization;
+        this.termination = termination;
+        this.increment = increment;
+        this.statement = block;
+    }
+
+    @Override
+    public void execute() {
+        for (initialization.execute(); termination.eval().asNumber() != 0; increment.execute()) {
+            statement.execute();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "for " + initialization + ", " + termination + ", " + increment + " " + statement;
+    }
+}

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

@@ -0,0 +1,28 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class WhileStatement implements Statement {
+    
+    private final Expression condition;
+    private final Statement statement;
+
+    public WhileStatement(Expression condition, Statement statement) {
+        this.condition = condition;
+        this.statement = statement;
+    }
+    
+    @Override
+    public void execute() {
+        while (condition.eval().asNumber() != 0) {
+            statement.execute();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "while " + condition + " " + statement;
+    }
+}