diff --git a/src/input.h b/src/input.h
new file mode 100644
index 0000000000..59e3eea719
--- /dev/null
+++ b/src/input.h
@@ -0,0 +1,134 @@
+#include <stdio.h>
+
+#ifndef INPUT_H
+#define INPUT_H
+
+// input //////////////////////////////////////////////////////////////////////
+
+class Input {
+ public:
+  virtual ~Input() { }
+  
+  virtual void dispose() = 0;
+
+  virtual int peek() = 0;
+
+  virtual int read() = 0;
+
+  virtual unsigned line() = 0;
+
+  virtual unsigned column() = 0;
+
+  void skipSpace() {
+    bool quit = false;
+    while (not quit) {
+      int c = peek();
+      switch (c) {
+      case ' ': case '\t': case '\n':
+        read();
+        break;
+
+      default: quit = true;
+      }
+    }
+  }
+};
+
+// file input /////////////////////////////////////////////////////////////////
+
+class FileInput : public Input {
+ public:
+  const char* file;
+  FILE* stream;
+  unsigned line_;
+  unsigned column_;
+  bool close;
+
+  FileInput(const char* file, FILE* stream = 0, bool close = true):
+    file(file), stream(stream), line_(1), column_(1), close(close)
+  { }
+
+  virtual ~FileInput() {
+    dispose();
+  }
+
+  virtual void dispose() {
+    if (stream and close) {
+      fclose(stream);
+      stream = 0;
+    }
+  }
+
+  virtual int peek() {
+    int c = getc(stream);
+    ungetc(c, stream);
+    return c;
+  }
+
+  virtual int read() {
+    int c = getc(stream);
+    if (c == '\n') {
+      ++ line_;
+      column_ = 1;
+    } else {
+      ++ column_;
+    }
+    return c;
+  }
+
+  virtual unsigned line() {
+    return line_;
+  }
+
+  virtual unsigned column() {
+    return column_;
+  }
+};
+
+// string input ///////////////////////////////////////////////////////////////
+
+class StringInput : public Input {
+ public:
+  const char* string;
+  unsigned position;
+  unsigned limit;
+  unsigned line_;
+  unsigned column_;
+
+  StringInput(const char* string);
+
+  virtual ~StringInput() { }
+
+  virtual void dispose() {
+    // do nothing
+  }
+
+  virtual int peek() {
+    if (position == limit) return -1;
+    return string[position];
+  }
+
+  virtual int read() {
+    int c = peek();
+    if (c >= 0) {
+      if (c == '\n') {
+        ++ line_;
+        column_ = 1;
+      } else {
+        ++ column_;
+      }
+      ++ position;
+    }
+    return c;
+  }
+
+  virtual unsigned line() {
+    return line_;
+  }
+
+  virtual unsigned column() {
+    return column_;
+  }
+};
+
+#endif//INPUT_H
diff --git a/src/output.h b/src/output.h
new file mode 100644
index 0000000000..06b6fac40e
--- /dev/null
+++ b/src/output.h
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <assert.h>
+
+#ifndef OUTPUT_H
+#define OUTPUT_H
+
+#define UNUSED __attribute__((unused))
+
+// output /////////////////////////////////////////////////////////////////////
+
+class Output {
+ public:
+  virtual ~Output() { }
+  
+  virtual void dispose() = 0;
+
+  virtual void write(const char* s) = 0;
+
+  void write(int i) {
+    static const int Size = 32;
+    char s[Size];
+    int c UNUSED = snprintf(s, Size, "%d", i);
+    assert(c > 0 and c < Size);
+    write(s);
+  }
+};
+
+// file output ////////////////////////////////////////////////////////////////
+
+class FileOutput : public Output {
+ public:
+  const char* file;
+  FILE* stream;
+  bool close;
+
+  FileOutput(const char* file, FILE* stream = 0, bool close = true):
+    file(file), stream(stream), close(close)
+  { }
+
+  virtual ~FileOutput() {
+    dispose();
+  }
+
+  virtual void dispose() {
+    if (stream and close) {
+      fclose(stream);
+      stream = 0;
+    }
+  }
+
+  virtual void write(const char* s) {
+    fputs(s, stream);
+  }
+
+  const char* filename() {
+    return file;
+  }
+};
+
+#endif//OUTPUT_H