Урок 4. Строки, оператор print

program.txt

@@ -0,0 +1,6 @@
+word = 2 + 2
+word2 = PI + word
+str = "a" * 5 + "ba" * 7 + "\n"
+print str * "3" * 2
+print "word = " + word + "\n"
+print "word2 = " + word2

src/com/annimon/ownlang/Main.java

@@ -5,6 +5,9 @@ import com.annimon.ownlang.parser.Lexer;
 import com.annimon.ownlang.parser.Parser;
 import com.annimon.ownlang.parser.Token;
 import com.annimon.ownlang.parser.ast.Statement;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 import java.util.List;
 
 /**
@@ -12,11 +15,9 @@ import java.util.List;
  */
 public final class Main {
 
-    public static void main(String[] args) {
-        final String input1 = "word = 2 + 2\nword2 = PI + word";
-//        final String input2 = "(GOLDEN_RATIO + 2) * #f";
-        final String input2 = "GOLDEN_RATIO";
-        final List<Token> tokens = new Lexer(input1).tokenize();
+    public static void main(String[] args) throws IOException {
+        final String input = new String( Files.readAllBytes(Paths.get("program.txt")), "UTF-8");
+        final List<Token> tokens = new Lexer(input).tokenize();
         for (Token token : tokens) {
             System.out.println(token);
         }
@@ -28,7 +29,5 @@ public final class Main {
         for (Statement statement : statements) {
             statement.execute();
         }
-        System.out.printf("%s = %f\n", "word", Variables.get("word"));
-        System.out.printf("%s = %f\n", "word2", Variables.get("word2"));
     }
 }

src/com/annimon/ownlang/lib/NumberValue.java

@@ -1,24 +1,29 @@
-package com.annimon.ownlang.parser.ast;
+package com.annimon.ownlang.lib;
 
 /**
  *
  * @author aNNiMON
  */
-public final class NumberExpression implements Expression {
+public final class NumberValue implements Value {
     
     private final double value;
-    
-    public NumberExpression(double value) {
+
+    public NumberValue(double value) {
         this.value = value;
     }
-
+    
     @Override
-    public double eval() {
+    public double asNumber() {
         return value;
     }
 
     @Override
-    public String toString() {
+    public String asString() {
         return Double.toString(value);
     }
+
+    @Override
+    public String toString() {
+        return asString();
+    }
 }

src/com/annimon/ownlang/lib/StringValue.java

@@ -0,0 +1,34 @@
+package com.annimon.ownlang.lib;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class StringValue implements Value {
+    
+    private final String value;
+
+    public StringValue(String value) {
+        this.value = value;
+    }
+    
+    @Override
+    public double asNumber() {
+        try {
+            return Double.parseDouble(value);
+        } catch (NumberFormatException e) {
+            return 0;
+        }
+    }
+
+    @Override
+    public String asString() {
+        return value;
+    }
+
+    @Override
+    public String toString() {
+        return asString();
+    }
+
+}

src/com/annimon/ownlang/lib/Value.java

@@ -0,0 +1,12 @@
+package com.annimon.ownlang.lib;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public interface Value {
+    
+    double asNumber();
+    
+    String asString();
+}

src/com/annimon/ownlang/lib/Variables.java

@@ -9,26 +9,27 @@ import java.util.Map;
  */
 public final class Variables {
 
-    private static final Map<String, Double> variables;
+    private static final NumberValue ZERO = new NumberValue(0);
+    private static final Map<String, Value> variables;
     
     static {
         variables = new HashMap<>();
-        variables.put("PI", Math.PI);
-        variables.put("ПИ", Math.PI);
-        variables.put("E", Math.E);
-        variables.put("GOLDEN_RATIO", 1.618);
+        variables.put("PI", new NumberValue(Math.PI));
+        variables.put("ПИ", new NumberValue(Math.PI));
+        variables.put("E", new NumberValue(Math.E));
+        variables.put("GOLDEN_RATIO", new NumberValue(1.618));
     }
     
     public static boolean isExists(String key) {
         return variables.containsKey(key);
     }
     
-    public static double get(String key) {
-        if (!isExists(key)) return 0;
+    public static Value get(String key) {
+        if (!isExists(key)) return ZERO;
         return variables.get(key);
     }
     
-    public static void set(String key, double value) {
+    public static void set(String key, Value value) {
         variables.put(key, value);
     }
 }

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

@@ -36,6 +36,7 @@ public final class Lexer {
             final char current = peek(0);
             if (Character.isDigit(current)) tokenizeNumber();
             else if (Character.isLetter(current)) tokenizeWord();
+            else if (current == '"') tokenizeText();
             else if (current == '#') {
                 next();
                 tokenizeHexNumber();
@@ -95,7 +96,37 @@ public final class Lexer {
             buffer.append(current);
             current = next();
         }
-        addToken(TokenType.WORD, buffer.toString());
+        
+        final String word = buffer.toString();
+        if (word.equals("print")) {
+            addToken(TokenType.PRINT);
+        } else {
+            addToken(TokenType.WORD, word);
+        }
+    }
+    
+    private void tokenizeText() {
+        next();// skip "
+        final StringBuilder buffer = new StringBuilder();
+        char current = peek(0);
+        while (true) {
+            if (current == '\\') {
+                current = next();
+                switch (current) {
+                    case '"': current = next(); buffer.append('"'); continue;
+                    case 'n': current = next(); buffer.append('\n'); continue;
+                    case 't': current = next(); buffer.append('\t'); continue;
+                }
+                buffer.append('\\');
+                continue;
+            }
+            if (current == '"') break;
+            buffer.append(current);
+            current = next();
+        }
+        next(); // skip closing "
+        
+        addToken(TokenType.TEXT, buffer.toString());
     }
     
     private char next() {

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

@@ -1,10 +1,11 @@
 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.VariabletExpression;
 import com.annimon.ownlang.parser.ast.Expression;
-import com.annimon.ownlang.parser.ast.NumberExpression;
+import com.annimon.ownlang.parser.ast.ValueExpression;
 import com.annimon.ownlang.parser.ast.Statement;
 import com.annimon.ownlang.parser.ast.UnaryExpression;
 import java.util.ArrayList;
@@ -37,6 +38,9 @@ public final class Parser {
     }
     
     private Statement statement() {
+        if (match(TokenType.PRINT)) {
+            return new PrintStatement(expression());
+        }
         return assignmentStatement();
     }
     
@@ -107,14 +111,17 @@ public final class Parser {
     private Expression primary() {
         final Token current = get(0);
         if (match(TokenType.NUMBER)) {
-            return new NumberExpression(Double.parseDouble(current.getText()));
+            return new ValueExpression(Double.parseDouble(current.getText()));
         }
         if (match(TokenType.HEX_NUMBER)) {
-            return new NumberExpression(Long.parseLong(current.getText(), 16));
+            return new ValueExpression(Long.parseLong(current.getText(), 16));
         }
         if (match(TokenType.WORD)) {
             return new VariabletExpression(current.getText());
         }
+        if (match(TokenType.TEXT)) {
+            return new ValueExpression(current.getText());
+        }
         if (match(TokenType.LPAREN)) {
             Expression result = expression();
             match(TokenType.RPAREN);

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

@@ -9,6 +9,10 @@ public enum TokenType {
     NUMBER,
     HEX_NUMBER,
     WORD,
+    TEXT,
+    
+    // keyword
+    PRINT,
     
     PLUS,
     MINUS,

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

@@ -1,5 +1,6 @@
 package com.annimon.ownlang.parser.ast;
 
+import com.annimon.ownlang.lib.Value;
 import com.annimon.ownlang.lib.Variables;
 
 /**
@@ -18,7 +19,7 @@ public final class AssignmentStatement implements Statement {
     
     @Override
     public void execute() {
-        final double result = expression.eval();
+        final Value result = expression.eval();
         Variables.set(variable, result);
     }
 

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

@@ -1,5 +1,9 @@
 package com.annimon.ownlang.parser.ast;
 
+import com.annimon.ownlang.lib.NumberValue;
+import com.annimon.ownlang.lib.StringValue;
+import com.annimon.ownlang.lib.Value;
+
 /**
  *
  * @author aNNiMON
@@ -16,14 +20,35 @@ public final class BinaryExpression implements Expression {
     }
 
     @Override
-    public double eval() {
+    public Value eval() {
+        final Value value1 = expr1.eval();
+        final Value value2 = expr2.eval();
+        if (value1 instanceof StringValue) {
+            final String string1 = value1.asString();
+            switch (operation) {
+                case '*': {
+                    final int iterations = (int) value2.asNumber();
+                    final StringBuilder buffer = new StringBuilder();
+                    for (int i = 0; i < iterations; i++) {
+                        buffer.append(string1);
+                    }
+                    return new StringValue(buffer.toString());
+                }
+                case '+':
+                default:
+                    return new StringValue(string1 + value2.asString());
+            }
+        }
+        
+        final double number1 = value1.asNumber();
+        final double number2 = value2.asNumber();
         switch (operation) {
-            case '-': return expr1.eval() - expr2.eval();
-            case '*': return expr1.eval() * expr2.eval();
-            case '/': return expr1.eval() / expr2.eval();
+            case '-': return new NumberValue(number1 - number2);
+            case '*': return new NumberValue(number1 * number2);
+            case '/': return new NumberValue(number1 / number2);
             case '+':
             default:
-                return expr1.eval() + expr2.eval();
+                return new NumberValue(number1 + number2);
         }
     }
 

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

@@ -1,10 +1,12 @@
 package com.annimon.ownlang.parser.ast;
 
+import com.annimon.ownlang.lib.Value;
+
 /**
  *
  * @author aNNiMON
  */
 public interface Expression {
     
-    double eval();
+    Value eval();
 }

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

@@ -0,0 +1,24 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class PrintStatement implements Statement {
+    
+    private final Expression expression;
+
+    public PrintStatement(Expression expression) {
+        this.expression = expression;
+    }
+
+    @Override
+    public void execute() {
+        System.out.print(expression.eval());
+    }
+
+    @Override
+    public String toString() {
+        return "print " + expression;
+    }
+}

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

@@ -1,5 +1,8 @@
 package com.annimon.ownlang.parser.ast;
 
+import com.annimon.ownlang.lib.NumberValue;
+import com.annimon.ownlang.lib.Value;
+
 /**
  *
  * @author aNNiMON
@@ -15,9 +18,9 @@ public final class UnaryExpression implements Expression {
     }
 
     @Override
-    public double eval() {
+    public Value eval() {
         switch (operation) {
-            case '-': return -expr1.eval();
+            case '-': return new NumberValue(-expr1.eval().asNumber());
             case '+':
             default:
                 return expr1.eval();

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

@@ -0,0 +1,32 @@
+package com.annimon.ownlang.parser.ast;
+
+import com.annimon.ownlang.lib.NumberValue;
+import com.annimon.ownlang.lib.StringValue;
+import com.annimon.ownlang.lib.Value;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class ValueExpression implements Expression {
+    
+    private final Value value;
+    
+    public ValueExpression(double value) {
+        this.value = new NumberValue(value);
+    }
+    
+    public ValueExpression(String value) {
+        this.value = new StringValue(value);
+    }
+
+    @Override
+    public Value eval() {
+        return value;
+    }
+
+    @Override
+    public String toString() {
+        return value.asString();
+    }
+}

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

@@ -1,5 +1,6 @@
 package com.annimon.ownlang.parser.ast;
 
+import com.annimon.ownlang.lib.Value;
 import com.annimon.ownlang.lib.Variables;
 
 /**
@@ -15,7 +16,7 @@ public final class VariabletExpression implements Expression {
     }
 
     @Override
-    public double eval() {
+    public Value eval() {
         if (!Variables.isExists(name)) throw new RuntimeException("Constant does not exists");
         return Variables.get(name);
     }