Abstract the file reading

This commit is contained in:
Eugen Wissner 2022-06-06 22:56:28 +02:00
parent aa6b2504bd
commit 473cd4e498
Signed by: belka
GPG Key ID: A27FDC1E8EE902C0
2 changed files with 345 additions and 23 deletions

View File

@ -3,7 +3,333 @@
*/ */
module elna.extended; module elna.extended;
import core.stdc.errno;
import core.stdc.stdio;
import std.sumtype;
import std.typecons;
import tanya.os.error;
import tanya.container.array;
import tanya.container.string;
/**
* File handle abstraction.
*/
struct File struct File
{ {
@disable this(this); /// Plattform dependent file type.
alias Handle = FILE*;
/// Uninitialized file handle value.
enum Handle invalid = null;
/**
* Relative position.
*/
enum Whence
{
/// Relative to the start of the file.
set = SEEK_SET,
/// Relative to the current cursor position.
currentt = SEEK_CUR,
/// Relative from the end of the file.
end = SEEK_END,
}
/**
* File open modes.
*/
enum Mode
{
/// Open the file for reading.
read = 1 << 0,
/// Open the file for writing. The stream is positioned at the beginning
/// of the file.
write = 1 << 1,
/// Open the file for writing and remove its contents.
truncate = 1 << 2,
/// Open the file for writing. The stream is positioned at the end of
/// the file.
append = 1 << 3,
}
private enum Status
{
invalid,
owned,
borrowed,
}
private union Storage
{
Handle handle;
ErrorCode errorCode;
}
private Storage storage;
private Status status = Status.invalid;
@disable this(scope return ref File f);
@disable this();
/**
* Closes the file.
*/
~this() @nogc nothrow
{
if (this.status == Status.owned)
{
fclose(this.storage.handle);
}
this.storage.handle = invalid;
this.status = Status.invalid;
}
/**
* Construct the object with the given system handle. The won't be claused
* in the descructor if this constructor is used.
*
* Params:
* handle = File handle to be wrapped by this structure.
*/
this(Handle handle) @nogc nothrow pure @safe
{
this.storage.handle = handle;
this.status = Status.borrowed;
}
/**
* Returns: Plattform dependent file handle.
*/
@property Handle handle() @nogc nothrow pure @trusted
{
return valid ? this.storage.handle : invalid;
}
/**
* Returns: An error code if an error has occurred.
*/
@property ErrorCode errorCode() @nogc nothrow pure @safe
{
return valid ? ErrorCode() : this.storage.errorCode;
}
/**
* Returns: Whether a valid, opened file is represented.
*/
@property bool valid() @nogc nothrow pure @safe
{
return this.status != Status.invalid;
}
/**
* Transfers the file into invalid state.
*
* Returns: The old file handle.
*/
Handle reset() @nogc nothrow pure @safe
{
if (!valid)
{
return invalid;
}
auto oldHandle = handle;
this.status = Status.invalid;
this.storage.errorCode = ErrorCode();
return oldHandle;
}
/**
* Sets stream position in the file.
*
* Params:
* offset = File offset.
* whence = File position to add the offset to.
*
* Returns: Error code if any.
*/
ErrorCode seek(size_t offset, Whence whence) @nogc nothrow
{
if (!valid)
{
return ErrorCode(ErrorCode.ErrorNo.badDescriptor);
}
if (fseek(this.storage.handle, offset, whence))
{
return ErrorCode(cast(ErrorCode.ErrorNo) errno);
}
return ErrorCode();
}
/**
* Returns: Current offset or an error.
*/
SumType!(ErrorCode, size_t) tell() @nogc nothrow
{
if (!valid)
{
return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
}
auto result = ftell(this.storage.handle);
if (result < 0)
{
return typeof(return)(ErrorCode(cast(ErrorCode.ErrorNo) errno));
}
return typeof(return)(cast(size_t) result);
}
/**
* Params:
* buffer = Destination buffer.
*
* Returns: Bytes read. $(D_PSYMBOL ErrorCode.ErrorNo.success) means that
* while reading the file an unknown error has occurred.
*/
SumType!(ErrorCode, size_t) read(ubyte[] buffer) @nogc nothrow
{
if (!valid)
{
return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
}
const bytesRead = fread(buffer.ptr, 1, buffer.length, this.storage.handle);
if (bytesRead == buffer.length || eof())
{
return typeof(return)(bytesRead);
}
return typeof(return)(ErrorCode());
}
/**
* Params:
* buffer = Source buffer.
*
* Returns: Bytes written. $(D_PSYMBOL ErrorCode.ErrorNo.success) means that
* while reading the file an unknown error has occurred.
*/
SumType!(ErrorCode, size_t) write(const(ubyte)[] buffer) @nogc nothrow
{
if (!valid)
{
return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
}
const bytesWritten = fwrite(buffer.ptr, 1, buffer.length, this.storage.handle);
if (bytesWritten == buffer.length)
{
return typeof(return)(buffer.length);
}
return typeof(return)(ErrorCode());
}
/**
* Returns: EOF status of the file.
*/
bool eof() @nogc nothrow
{
return valid && feof(this.storage.handle) != 0;
}
/**
* Constructs a file object that will be closed in the destructor.
*
* Params:
* filename = The file to open.
*
* Returns: Opened file or an error.
*/
static File open(const(char)* filename, BitFlags!Mode mode) @nogc nothrow
{
char[3] modeBuffer = "\0\0\0";
if (mode.truncate)
{
modeBuffer[0] = 'w';
if (mode.read)
{
modeBuffer[1] = '+';
}
}
else if (mode.append)
{
modeBuffer[0] = 'a';
if (mode.read)
{
modeBuffer[1] = '+';
}
}
else if (mode.read)
{
modeBuffer[0] = 'r';
if (mode.write)
{
modeBuffer[1] = '+';
}
}
auto newHandle = fopen(filename, modeBuffer.ptr);
auto newFile = File(newHandle);
if (newHandle is null)
{
newFile.status = Status.invalid;
newFile.storage.errorCode = ErrorCode(cast(ErrorCode.ErrorNo) errno);
}
else
{
if (mode == BitFlags!Mode(Mode.write))
{
rewind(newHandle);
}
newFile.status = Status.owned;
}
return newFile;
}
}
/**
* Reads the whole file and returns its contents.
*
* Params:
* sourceFilename = Source filename.
*
* Returns: File contents or an error.
*
* See_Also: $(D_PSYMBOL File.read)
*/
SumType!(ErrorCode, Array!ubyte) readFile(String sourceFilename) @nogc
{
enum size_t bufferSize = 255;
auto sourceFile = File.open(sourceFilename.toStringz, BitFlags!(File.Mode)(File.Mode.read));
if (!sourceFile.valid)
{
return typeof(return)(sourceFile.errorCode);
}
Array!ubyte sourceText;
size_t totalRead;
size_t bytesRead;
do
{
sourceText.length = sourceText.length + bufferSize;
const readStatus = sourceFile
.read(sourceText[totalRead .. $].get)
.match!(
(ErrorCode errorCode) => nullable(errorCode),
(size_t bytesRead_) {
bytesRead = bytesRead_;
return Nullable!ErrorCode();
}
);
if (!readStatus.isNull)
{
return typeof(return)(readStatus.get);
}
totalRead += bytesRead;
}
while (bytesRead == bufferSize);
sourceText.length = totalRead;
return typeof(return)(sourceText);
} }

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@ -5,47 +5,43 @@ import elna.lexer;
import elna.parser; import elna.parser;
import elna.generator; import elna.generator;
import elna.ir; import elna.ir;
import elna.extended;
import std.sumtype;
import std.typecons;
import tanya.container.array;
import tanya.container.string; import tanya.container.string;
import tanya.memory.allocator; import tanya.memory.allocator;
import tanya.memory.mmappool; import tanya.memory.mmappool;
import tanya.os.error;
private char[] readSource(size_t N)(string source, out char[N] buffer) @nogc private Nullable!String readSource(string source) @nogc
{ {
memcpy(buffer.ptr, source.ptr, source.length + 1); enum size_t bufferSize = 255;
buffer[source.length] = '\0'; auto sourceFilename = String(source);
auto handle = fopen(buffer.ptr, "r");
if (handle is null)
{
perror(buffer.ptr);
return null;
}
fseek(handle, 0, SEEK_END);
size_t fsize = ftell(handle);
rewind(handle);
fread(buffer.ptr, fsize, 1, handle); return readFile(sourceFilename).match!(
fclose(handle); (ErrorCode errorCode) {
buffer[fsize] = '\0'; perror(sourceFilename.toStringz);
return Nullable!String();
return buffer[0 .. fsize]; },
(Array!ubyte contents) => nullable(String(cast(char[]) contents.get))
);
} }
int main(string[] args) int main(string[] args)
{ {
char[255] buffer;
defaultAllocator = MmapPool.instance; defaultAllocator = MmapPool.instance;
if (args.length < 2) if (args.length < 2)
{ {
return 4; return 4;
} }
auto sourceText = readSource(args[1], buffer); auto sourceText = readSource(args[1]);
if (sourceText is null) if (sourceText.isNull)
{ {
return 3; return 3;
} }
auto tokens = lex(sourceText); auto tokens = lex(sourceText.get.get);
if (tokens.length == 0) if (tokens.length == 0)
{ {
printf("Lexical analysis failed.\n"); printf("Lexical analysis failed.\n");