Hack in a binary file writer.

example/FileWriter.mag

@@ -0,0 +1,12 @@
+// A few examples of reading a file.
+
+import io
+
+create("example/out.magc") use with
+    it writeByte(0)
+    it writeByte(128)
+    it writeByte(255)
+    it writeInt(1234567)
+end
+
+print("Done")

src/com/stuffwithstuff/magpie/intrinsic/IOMethods.java

@@ -13,8 +13,14 @@
 import com.stuffwithstuff.magpie.interpreter.Context;
 import com.stuffwithstuff.magpie.interpreter.Obj;
 import com.stuffwithstuff.magpie.util.FileReader;
+import com.stuffwithstuff.magpie.util.FileWriter;
 
 public class IOMethods {
+  // TODO(bob): There is a big hack here. We use the same "File" Magpie class
+  // to encapsulate both a FileReader and a FileWriter. But the read and
+  // write methods assume one or the other and will blow up if you use the
+  // wrong one.
+
   // TODO(bob): Hackish.
   @Def("_setClasses(== File)")
   public static class SetClasses implements Intrinsic {
@@ -28,8 +34,13 @@ public Obj invoke(Context context, Obj left, Obj right) {
   @Doc("Closes the file.")
   public static class Close implements Intrinsic {
     public Obj invoke(Context context, Obj left, Obj right) {
-      FileReader reader = (FileReader)left.getValue();
-      reader.close();
+      if (left.getValue() instanceof FileReader) {
+        FileReader reader = (FileReader)left.getValue();
+        reader.close();
+      } else {
+        FileWriter writer = (FileWriter)left.getValue();
+        writer.close();
+      }
       return context.nothing();
     }
   }
@@ -49,6 +60,22 @@ public Obj invoke(Context context, Obj left, Obj right) {
       }
     }
   }
+
+  @Def("create(path is String)")
+  @Doc("Creates a new file at the given path.")
+  public static class Create implements Intrinsic {
+    public Obj invoke(Context context, Obj left, Obj right) {
+      String path = right.asString();
+
+      FileWriter writer;
+      try {
+        writer = new FileWriter(path);
+        return context.instantiate(sFileClass, writer);
+      } catch (IOException e) {
+        throw context.error("IOError", "Could not open file.");
+      }
+    }
+  }
 
   @Def("(is File) isOpen")
   @Doc("Returns true if the file is open.")
@@ -106,6 +133,34 @@ public Obj invoke(Context context, Obj left, Obj right) {
       }
     }
   }
+
+  @Def("(is File) writeByte(is Int)")
+  @Doc("Writes the given byte (value from 0 to 255 inclusive) to this File.")
+  public static class WriteByte implements Intrinsic {
+    public Obj invoke(Context context, Obj left, Obj right) {
+      FileWriter writer = (FileWriter)left.getValue();
+      try {
+        writer.writeByte(right.asInt());
+        return right;
+      } catch (IOException e) {
+        throw context.error("IOError", "Could not write.");
+      }
+    }
+  }
+
+  @Def("(is File) writeInt(is Int)")
+  @Doc("Writes the given int to this File.")
+  public static class WriteInt implements Intrinsic {
+    public Obj invoke(Context context, Obj left, Obj right) {
+      FileWriter writer = (FileWriter)left.getValue();
+      try {
+        writer.writeInt(right.asInt());
+        return right;
+      } catch (IOException e) {
+        throw context.error("IOError", "Could not write.");
+      }
+    }
+  }
 
   @Def("(is Directory) _contents")
   @Doc("Gets the contents of the directory.")

src/com/stuffwithstuff/magpie/util/FileWriter.java

@@ -0,0 +1,38 @@
+package com.stuffwithstuff.magpie.util;
+
+import java.io.DataOutputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+public class FileWriter {
+  public FileWriter(String path) throws IOException {
+    mStream = new DataOutputStream(new FileOutputStream(path));
+  }
+
+  public boolean isOpen() {
+    return mStream != null;
+  }
+
+  public void close() {
+    // Do nothing if already closed.
+    if (mStream == null) return;
+
+    try {
+      mStream.close();
+      mStream = null;
+    } catch (IOException e) {
+      // TODO Auto-generated catch block
+      e.printStackTrace();
+    }
+  }
+
+  public void writeByte(int value) throws IOException {
+    mStream.writeByte(value);
+  }
+
+  public void writeInt(int value) throws IOException {
+    mStream.writeInt(value);
+  }
+
+  private DataOutputStream mStream;
+}