Урок 9. Функции

program.txt

@@ -21,7 +21,7 @@ if (40 < 50 || 50 > 60) {
     i = 0
     print "while"
     while (i < 10) {
-        print "i = " + i + "\n"
+        print "i = " + i + sin(i) + "\n"
         i = i + 1
     }
     print "for"
@@ -29,4 +29,7 @@ if (40 < 50 || 50 > 60) {
         print "i = " + i + "\n"
     }
 }
-else print "false"
+else print "false"
+
+print "sin(PI) = " + sin(PI/2)
+echo(1,2,3,"4","5","text",sin(0),cos(0),sin(PI),cos(PI),PI)

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

@@ -0,0 +1,10 @@
+package com.annimon.ownlang.lib;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public interface Function {
+
+    Value execute(Value... args);
+}

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

@@ -0,0 +1,49 @@
+package com.annimon.ownlang.lib;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class Functions {
+
+    private static final NumberValue ZERO = new NumberValue(0);
+    private static final Map<String, Function> functions;
+    
+    static {
+        functions = new HashMap<>();
+        functions.put("sin", new Function() {
+
+            @Override
+            public Value execute(Value... args) {
+                if (args.length != 1) throw new RuntimeException("One arg expected");
+                return new NumberValue(Math.sin(args[0].asNumber()));
+            }
+        });
+        functions.put("cos", (Function) (Value... args) -> {
+            if (args.length != 1) throw new RuntimeException("One arg expected");
+            return new NumberValue(Math.cos(args[0].asNumber()));
+        });
+        functions.put("echo", args -> {
+            for (Value arg : args) {
+                System.out.println(arg.asString());
+            }
+            return ZERO;
+        });
+    }
+    
+    public static boolean isExists(String key) {
+        return functions.containsKey(key);
+    }
+    
+    public static Function get(String key) {
+        if (!isExists(key)) throw new RuntimeException("Unknown function " + key);
+        return functions.get(key);
+    }
+    
+    public static void set(String key, Function function) {
+        functions.put(key, function);
+    }
+}

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

@@ -65,6 +65,9 @@ public final class Parser {
         if (match(TokenType.FOR)) {
             return forStatement();
         }
+        if (get(0).getType() == TokenType.WORD && get(1).getType() == TokenType.LPAREN) {
+            return new FunctionStatement(function());
+        }
         return assignmentStatement();
     }
     
@@ -114,6 +117,16 @@ public final class Parser {
         return new ForStatement(initialization, termination, increment, statement);
     }
     
+    private FunctionalExpression function() {
+        final String name = consume(TokenType.WORD).getText();
+        consume(TokenType.LPAREN);
+        final FunctionalExpression function = new FunctionalExpression(name);
+        while (!match(TokenType.RPAREN)) {
+            function.addArgument(expression());
+            match(TokenType.COMMA);
+        }
+        return function;
+    }
     
     private Expression expression() {
         return logicalOr();
@@ -241,6 +254,9 @@ public final class Parser {
         if (match(TokenType.HEX_NUMBER)) {
             return new ValueExpression(Long.parseLong(current.getText(), 16));
         }
+        if (get(0).getType() == TokenType.WORD && get(1).getType() == TokenType.LPAREN) {
+            return function();
+        }
         if (match(TokenType.WORD)) {
             return new VariableExpression(current.getText());
         }

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

@@ -0,0 +1,24 @@
+package com.annimon.ownlang.parser.ast;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class FunctionStatement implements Statement {
+    
+    private final FunctionalExpression function;
+    
+    public FunctionStatement(FunctionalExpression function) {
+        this.function = function;
+    }
+
+    @Override
+    public void execute() {
+        function.eval();
+    }
+
+    @Override
+    public String toString() {
+        return function.toString();
+    }
+}

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

@@ -0,0 +1,45 @@
+package com.annimon.ownlang.parser.ast;
+
+import com.annimon.ownlang.lib.Functions;
+import com.annimon.ownlang.lib.Value;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class FunctionalExpression implements Expression {
+    
+    private final String name;
+    private final List<Expression> arguments;
+    
+    public FunctionalExpression(String name) {
+        this.name = name;
+        arguments = new ArrayList<>();
+    }
+    
+    public FunctionalExpression(String name, List<Expression> arguments) {
+        this.name = name;
+        this.arguments = arguments;
+    }
+    
+    public void addArgument(Expression arg) {
+        arguments.add(arg);
+    }
+
+    @Override
+    public Value eval() {
+        final int size = arguments.size();
+        final Value[] values = new Value[size];
+        for (int i = 0; i < size; i++) {
+            values[i] = arguments.get(i).eval();
+        }
+        return Functions.get(name).execute(values);
+    }
+
+    @Override
+    public String toString() {
+        return name + "(" + arguments.toString() + ")";
+    }
+}