Nice/stdlib/nice/io file.nice,NONE,1.1

Update of /cvsroot/nice/Nice/stdlib/nice/io
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv28672/stdlib/nice/io

Added Files:
	file.nice 
Log Message:
Some useful odds and ends

--- NEW FILE: file.nice ---
/****************************************************************************
 *                                 N I C E                                  *
 *              A high-level object-oriented research language              *
 *                         (c) Daniel Bonniot 2003                          *
 *                                                                          *
 *  This package is free software; you can redistribute it and/or modify    *
 *  it under the terms of the GNU General Public License as published by    *
 *  Free Software Foundation; either version 2 of the License, or (at your  *
 *  option) any later version.                                              *
 *                                                                          *
 *  As a special exception, the copyright holders of this library give you  *
 *  permission to link this library with independent modules to produce an  *
 *  executable, regardless of the license terms of these independent        *
 *  modules, and to copy and distribute the resulting executable under      *
 *  terms of your choice.                                                   *
 ****************************************************************************/

/**
 * Methods for operating on files and directories.
 *
 * @author Bryn Keller <[email protected]>
 */

package nice.io;

import nice.functional;

class File = native java.io.File;

/** Path concatenation */
<T> File `/`(File dir, !T file) = new File(dir.getCanonicalPath() 
				     + separator + file.toString());

private class NiceFilter implements java.io.FileFilter {
  File->boolean acceptFunc;
  accept(file) = acceptFunc(file);
}

/**
 * Returns all the files and directories in the given directory.
 * If the filter function is provided, then only files and
 * directories for which the filter function returns true will
 * be included.
 */
File[] listDir(File dir, File->boolean filter = always(true)) =
  cast(java.io.File.listFiles(dir, new NiceFilter(acceptFunc: filter)));


/**
 * Traverses a directory structure and returns a preordered
 * list of all files/directories in
 * all subdirectories which match the filter.
 */
void->File traverse(File dir, File->boolean filter = always(true))
  requires dir.isDirectory() :  "Only directories can be passed to traverse()."
{ 
  //Explicit stack management, since 
  //Java doesn't do tail call elimination...
  let stack = new Stack();
  var current = dir.listDir(filter).iterator();
  return () => {
    while(!current.hasNext()) {
      if (stack.isEmpty()) {
	stop();
      } else {
	current = stack.pop();
      } 
    }
    let f = current.next();
    if (f.isDirectory()) {
      stack.push(current);
      current = f.listDir(filter).iterator();
    }
    return f;
  };
}

private let String TEST = "This is a test.\nThis is only a test";


/** 
 * Opens a file, writes the given text to it, and closes the file.
 */
void write(File file, String text, ?String encoding = null) 
  requires file.isFile() : "Only files can be written"
{
  let writer = (encoding == null)
               ? new java.io.FileWriter(file)
               : new java.io.OutputStreamWriter(
				new java.io.FileOutputStream(file),
				encoding);
  using(writer) {
    writer.write(text);
  }
}

var int blockSize = 2048;

/**
 * Opens a file and reads the contents into a String.
 */
String read(File file, ?String encoding = null) 
    requires file.exists(): "File " file " does not exist",
            file.isFile(): file + " is not a normal file. Only normal files can be read."
{
  let chars = new char[blockSize];
  let buff = new StringBuffer();
  let input = new BufferedReader(
                    (encoding == null) 
                        ? new java.io.FileReader(file)
                        : new java.io.InputStreamReader(
			                new java.io.FileInputStream(file), encoding)
                            );
  using(input) {
    var count = 0;
    while((count = input.read(chars, 0, blockSize)) > 0)
      buff.append(chars, 0, count);
  }
  return buff.toString();
}

/**
 * Opens a file and returns a generator which yields the lines contained in the file,
 * one by one.
 */
void->String readLines(File file, ?encoding = null)
    requires file.exists(): "File " file " does not exist",
            file.isFile(): file + " is not a normal file. Only normal files can be read."
{
  let input = new BufferedReader(
                    (encoding == null) 
                        ? new java.io.FileReader(file)
                        : new java.io.InputStreamReader(
			                new java.io.FileInputStream(file), encoding)
                            );
  void close() { input.close(); stop(); }
  return ()=> try {
    return input.readLine() || close();
    } catch (Throwable t) {
        input.close();
        throw t;
    }
}

/**
 * Returns the standard temp directory. 
 */
File getTempDir() {
  //There must be a better way?
  let f = createTempFile("getTempDir", "test");
  let d = f.getParentFile().notNull();
  f.delete();
  return d;
}

void _testReadWriteFile() {
  let f = createTempFile("_testReadWriteFile", ".tmp");
  f.write(TEST);
  let s = f.read();
  assert s.equals(TEST);
  f.delete();
}

void _testReadWriteWithEncoding() {
  let f = createTempFile("_testReadWriteFileWithEncoding", ".tmp");
  f.write(TEST, "UTF-16");
  let s2 = f.read("UTF-16");
  assert s2.equals(TEST);
  f.delete();
}

class DirFixture implements Disposable {
  List<File> dirs = [];
  List<File> files = [];
  {
    /*
      one
        a.txt
	b.bmp
        two
	    c.txt
	    three
	four
	    d.txt
    */
    let tmpdir = getTempDir();
    let one = tmpdir/"one";
    let two = one/"two";
    let three = two/"three";
    let four = one/"four";
    dirs = [one,two,three,four];
    dirs.map(mkdir);
    let f1 = new File(one, "a.txt");
    let f2 = new File(one, "b.bmp");
    let f3 = new File(two, "c.txt");
    let f4 = new File(four, "d.txt");
    files = [f1,f2,f3,f4];
    files.map(createNewFile);
  }
  dispose() {
    for(f:files) delete(f);
    for(f:dirs) delete(f);
  }
}

void _testTraverse() {
  using(new DirFixture()) {
    let tmpdir = getTempDir();
    let gen = traverse(tmpdir/"one");
    void test(File file) {
      let res = gen();
      assert res.equals(file) : "Expected " + file + " got " + res;
    }
    test(tmpdir/"one"/"two");  
    test(tmpdir/"one"/"two"/"three");
    test(tmpdir/"one"/"two"/"c.txt");
    test(tmpdir/"one"/"four");
    test(tmpdir/"one"/"four"/"d.txt");
    test(tmpdir/"one"/"a.txt");
    test(tmpdir/"one"/"b.bmp");    
    try {
      gen();
      assert false;
    } catch (GeneratorEnd e) {}
  }
}

void _testTraverseWithFilter() {
  using(new DirFixture()) {
    let tmpdir = getTempDir();
    let gen = traverse(tmpdir/"one", isDirectory);
    void test(File file) {
      let res = gen();
      assert res.equals(file) : "Expected " + file + " got " + res;
    }
    test(tmpdir/"one"/"two");  
    test(tmpdir/"one"/"two"/"three");
    test(tmpdir/"one"/"four");
    try {
      gen();
      assert false;
    } catch (GeneratorEnd e) {}
  }
}

void _testTraverseWithFilter2() {
  using(new DirFixture()) {
    let tmpdir = getTempDir();
    let gen = traverse(tmpdir/"one", 
		File f => f.toString().endsWith(".bmp")
		         || f.isDirectory());
    void test(File file) {
      let res = gen();
      assert res.equals(file) : "Expected " + file + " got " + res;
    }
    test(tmpdir/"one"/"two");  
    test(tmpdir/"one"/"two"/"three");
    test(tmpdir/"one"/"four");
    test(tmpdir/"one"/"b.bmp");    
    try {
      gen();
      assert false;
    } catch (GeneratorEnd e) {}
  }
}






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