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* Copyright by the contributors to the Dafny Project
* SPDX-License-Identifier: MIT
*******************************************************************************/
package DafnyLibraries;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import dafny.DafnySequence;
import dafny.Tuple2;
import dafny.Tuple3;
import dafny.TypeDescriptor;
public class FileIO {
/**
* Attempts to read all bytes from the file at {@code path}, and returns a tuple of the following values:
* <dl>
* <dt>{@code isError}</dt>
* <dd>true iff an exception was thrown during path string conversion or when reading the file</dd>
* <dt>{@code bytesRead}</dt>
* <dd>the sequence of bytes read from the file, or an empty sequence if {@code isError} is true</dd>
* <dt>{@code errorMsg}</dt>
* <dd>the error message of the thrown exception if {@code isError} is true, or an empty sequence otherwise</dd>
* </dl>
* <p>
* We return these values individually because {@code Result} is not defined in the runtime but instead in library code.
* It is the responsibility of library code to construct an equivalent {@code Result} value.
*/
public static Tuple3<Boolean, DafnySequence<? extends Byte>, DafnySequence<? extends Character>>
INTERNAL_ReadBytesFromFile(DafnySequence<? extends Character> path) {
try {
final Path pathObj = dafnyStringToPath(path);
final DafnySequence<Byte> readBytes = DafnySequence.fromBytes(Files.readAllBytes(pathObj));
return Tuple3.create(false, readBytes, DafnySequence.empty(TypeDescriptor.CHAR));
} catch (Exception ex) {
return Tuple3.create(true, DafnySequence.empty(TypeDescriptor.BYTE), stackTraceToDafnyString(ex));
}
}
/**
* Attempts to write {@code bytes} to the file at {@code path}, creating nonexistent parent directories as necessary,
* and returns a tuple of the following values:
* <dl>
* <dt>{@code isError}</dt>
* <dd>true iff an exception was thrown during path string conversion or when writing to the file</dd>
* <dt>{@code errorMsg}</dt>
* <dd>the error message of the thrown exception if {@code isError} is true, or an empty sequence otherwise</dd>
* </dl>
* <p>
* We return these values individually because {@code Result} is not defined in the runtime but instead in library code.
* It is the responsibility of library code to construct an equivalent {@code Result} value.
*/
public static Tuple2<Boolean, DafnySequence<? extends Character>>
INTERNAL_WriteBytesToFile(DafnySequence<? extends Character> path, DafnySequence<? extends Byte> bytes) {
try {
final Path pathObj = dafnyStringToPath(path);
createParentDirs(pathObj);
// It's safe to cast `bytes` to `DafnySequence<Byte>` since the cast value is immediately consumed
@SuppressWarnings("unchecked")
final byte[] byteArr = DafnySequence.toByteArray((DafnySequence<Byte>) bytes);
Files.write(pathObj, byteArr);
return Tuple2.create(false, DafnySequence.empty(TypeDescriptor.CHAR));
} catch (Exception ex) {
return Tuple2.create(true, stackTraceToDafnyString(ex));
}
}
/**
* Returns a Path constructed from the given Dafny string.
*/
private static final Path dafnyStringToPath(final DafnySequence<? extends Character> path) {
return Paths.get(new String((char[]) path.toArray().unwrap()));
}
/**
* Creates the nonexistent parent directory(-ies) of the given path.
*/
private static final void createParentDirs(final Path path) throws IOException {
final Path parentDir = path.toAbsolutePath().getParent();
if (parentDir == null) {
return;
}
Files.createDirectories(parentDir);
}
private static final DafnySequence<Character> stackTraceToDafnyString(final Throwable t) {
final StringWriter stringWriter = new StringWriter();
final PrintWriter printWriter = new PrintWriter(stringWriter);
t.printStackTrace(printWriter);
final String str = stringWriter.toString();
return DafnySequence.of(str.toCharArray());
}
}
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