adding symbols

src/main/java/com/vectron/fcl/Fcl.java

@@ -11,6 +11,7 @@ import com.vectron.fcl.types.Num;
 import com.vectron.fcl.types.Obj;
 import com.vectron.fcl.types.Primitive;
 import com.vectron.fcl.types.Str;
+import com.vectron.fcl.types.Symbol;
 import com.vectron.fcl.types.Word;
 
 import java.io.IOException;
@@ -18,7 +19,9 @@ import java.io.Reader;
 import java.io.StringReader;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 public class Fcl {
@@ -35,6 +38,7 @@ public class Fcl {
     private Reader reader;
     private Mode mode = Mode.INTERPRET;
     private final Object[] heap;
+    private final Map<String, Symbol> symbols = new HashMap<>();
     private int dp = SCRATCH_SIZE;
     private int ip = 0;
     private boolean trace = false;
@@ -567,13 +571,15 @@ public class Fcl {
     private Obj recognize(String token) {
         Obj str = recognizeStr(token);
         if (str != null) return str;
+        Obj symbol = recognizeSymbol(token);
+        if (symbol != null) return symbol;
         return Num.parse(token);
     }
 
-    private Obj recognizeStr(String firstToken) {
-        if (!firstToken.startsWith("'")) return null;
-        StringBuilder str = new StringBuilder(firstToken.substring(1));
-        if (firstToken.endsWith("'") && firstToken.length() > 1) {
+    private Obj recognizeStr(String token) {
+        if (!token.startsWith("'")) return null;
+        StringBuilder str = new StringBuilder(token.substring(1));
+        if (token.endsWith("'") && token.length() > 1) {
             str.setLength(str.length() - 1);
         } else {
             str.append(" ");
@@ -586,6 +592,18 @@ public class Fcl {
         return new Str(str.toString());
     }
 
+    private Obj recognizeSymbol(String token) {
+        return token.startsWith(":") && token.length() > 1
+                ? symbol(token.substring(1))
+                : null;
+    }
+
+    private Symbol symbol(String name) {
+        if (!symbols.containsKey(name))
+            symbols.put(name, new Symbol(name));
+        return symbols.get(name);
+    }
+
     private void innerLoop(int address) {
         ip = address;
         Word word = (Word) heap[ip++];

src/main/java/com/vectron/fcl/FclTypeAdapter.java

@@ -17,6 +17,7 @@ import com.vectron.fcl.types.Obj;
 import com.vectron.fcl.types.Quot;
 import com.vectron.fcl.types.Range;
 import com.vectron.fcl.types.Str;
+import com.vectron.fcl.types.Symbol;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -32,6 +33,7 @@ public class FclTypeAdapter extends TypeAdapter<Object> {
         register("bool", Bool.class);
         register("str", Str.class);
         register("dic", Dic.class);
+        register("sym", Symbol.class);
         register("lst", Lst.class);
         register("nil", Nil.class);
         register("quot", Quot.class);

src/main/java/com/vectron/fcl/types/Symbol.java

@@ -0,0 +1,63 @@
+package com.vectron.fcl.types;
+
+import com.vectron.fcl.exceptions.TypeMismatched;
+
+public class Symbol implements Obj {
+    private final String symbol;
+
+    public Symbol(String symbol) {
+        this.symbol = symbol;
+    }
+
+    @Override
+    public long longValue() {
+        throw new TypeMismatched(this, "long");
+    }
+
+    @Override
+    public int intValue() {
+        throw new TypeMismatched(this, "int");
+    }
+
+    @Override
+    public double doubleValue() {
+        throw new TypeMismatched(this, "double");
+    }
+
+    @Override
+    public boolean boolValue() {
+        throw new TypeMismatched(this, "bool");
+    }
+
+    @Override
+    public Num asNum() {
+        return null;
+    }
+
+    @Override
+    public Str asStr() {
+        return new Str(symbol);
+    }
+
+    @Override
+    public Object value() {
+        return symbol;
+    }
+
+    @Override
+    public Object unwrap() {
+        return symbol;
+    }
+
+    @Override
+    public String toString() {
+        return ":" + symbol;
+    }
+
+    @Override
+    public int compareTo(Obj other) {
+        return other instanceof Symbol
+                ? symbol.compareTo(((Symbol) other).symbol)
+                : -1;
+    }
+}

src/test/java/com/vectron/fcl/FclTest.java

@@ -1187,6 +1187,16 @@ public class FclTest {
                 evalPop("#[ 'headers' #[ 'Content-Type' 'text/plain' ]# 'content' #[ 'a' 1 ]# ]# +json-type").toString());
     }
 
+    @Test
+    public void testSymbols() {
+        assertEquals(":my-symbol", evalPop(":my-symbol").toString());
+        assertEquals(true, evalPop(":my-symbol :my-symbol =").boolValue());
+        assertEquals(false, evalPop(":my-symbol :my-symbol !=").boolValue());
+        assertEquals(false, evalPop(":my-symbol :my-symbol2 =").boolValue());
+        assertEquals(true, evalPop(":my-symbol :my-symbol2 !=").boolValue());
+        assertEquals(true, evalPop(": tst :my-symbol :my-symbol = ; tst").boolValue());
+    }
+
     private String transcript() {
         return transcript.content();
     }