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Copy pathFlags.java
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259 lines (229 loc) · 9.03 KB
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package com.github.yin.flags;
import com.github.yin.flags.analysis.UsagePrinter;
import com.github.yin.flags.annotations.ClassScanner;
import com.google.common.annotations.VisibleForTesting;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
/**
* Parses program arguments in a specified format and initializes registered static class fields in different
* application components. Flags provides static API to the client application and client should not attempt to
* manipulate own instances of Flags. One exception might be testing. Here, we provide method
* {@link Flags#initForTesting(Map)}).
*
* Example:
* <pre>{@code
* @FlagDesc("Processes report in current directory.")
* public static class ReportMain {
*
* @FlagDesc("if 'true', prints additional information")
* static final Flag<String> verbose = Flags.string("verbose");
*
* public static main(String[] args) {
* Flags.init(args);
* if (foo.get().equals("true")) {
* // ...
* } else if (foo.get().equals("false")) {
* // ...
* } else {
* Flags.printUsage("com.example");
* }
* }
* }
* }</pre>
*
* @author yin
*/
public class Flags {
private static Flags instance;
private final ClassScanner classScanner;
private final ClassMetadataIndex classMetadataIndex;
private final FlagIndex<Flag<?>> flagIndex;
private final FlagIndex<FlagMetadata> flagMetadataIndex;
private final BasicFlag typeConversion;
/**
* Initializes flag values from command-line style arguments.
* @param args command-line arguments to parse values from
* @param packages list of package roots to scan flags
*/
public static void parse(String[] args, Iterable<String> packages) {
instance().scan(packages);
instance().parseArguments(args);
}
/**
* Returns flag value accessor for <code>String</code> type. See create().
*/
public static Flag<String> create(String defaultz) {
return new BasicFlag.StringFlag(defaultz);
}
/** Prints user-readable usage help for all flags in a given package */
public static void printUsage(String packagePrefix) {
instance().printUsageForPackage(packagePrefix);
}
/**
* Indexes flag values from a <code>Map</code>. This is useful for mocking flag values in
* integration testing. Please do not misuse this function, there will be better way to inject
* your logic into flag processing, surely use this only in your tests.
* @param options Map of flags and their intended values
*/
@VisibleForTesting
public static void initForTesting(Map<String, String> options) {
instance().indexMap(options);
}
@VisibleForTesting
static ClassMetadataIndex classMetadata() {
return instance().classMetadataIndex;
}
@VisibleForTesting
static FlagIndex flagMetadata() {
return instance().flagMetadataIndex;
}
private void scan(Iterable<String> packages) {
for (String pkg : packages) {
classScanner.scanPackage(pkg, flagMetadataIndex, classMetadataIndex);
}
}
private void printUsageForPackage(String packageProfix) {
synchronized (this) {
classScanner.scanPackage(packageProfix, flagMetadataIndex, classMetadataIndex);
}
new UsagePrinter().printUsage(flagMetadataIndex, classMetadataIndex, System.out);
}
private String scanCallerClass() throws ClassNotFoundException {
String className = getCallerClassName();
synchronized (this) {
classScanner.scanClass(className, flagMetadataIndex, classMetadataIndex);
}
return className;
}
private static Flags instance() {
synchronized (Flags.class) {
if (instance == null) {
instance = new Flags(new ClassScanner(), new ClassMetadataIndex(), new FlagIndex<>(),
new FlagIndex<>(), new BasicFlag());
}
}
return instance;
}
private Flags(ClassScanner classScanner, ClassMetadataIndex classMetadataIndex, FlagIndex<Flag<?>> flagIndex, FlagIndex<FlagMetadata> flagMetadataIndex, BasicFlag typeConversion) {
this.classScanner = classScanner;
this.classMetadataIndex = classMetadataIndex;
this.flagIndex = flagIndex;
this.flagMetadataIndex = flagMetadataIndex;
this.typeConversion = typeConversion;
}
private void parseArguments(String[] args) {
ArgsAcceptor acceptor = new ArgsAcceptor(flagIndex, typeConversion);
acceptor.start();
for (String arg : args) {
if (arg.startsWith("--")) {
acceptor.key(arg.substring(2), arg);
} else if (arg.startsWith("-")) {
acceptor.key(arg.substring(1), arg);
} else {
acceptor.value(arg);
}
}
acceptor.end();
}
private void indexMap(Map<String, String> options) {
ArgsAcceptor acceptor = new ArgsAcceptor(flagIndex, typeConversion);
acceptor.start();
for (Map.Entry<String, String> option : options.entrySet()) {
acceptor.key(option.getKey(), option.getKey());
acceptor.value(option.getValue());
}
acceptor.end();
}
private String getCallerClassName() {
StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
String myType = Flags.class.getCanonicalName();
String threadType = Thread.class.getCanonicalName();
for (StackTraceElement e : stackTrace) {
if (!e.getClassName().equals(myType) && !e.getClassName().equals(threadType)) {
return e.getClassName();
}
}
return null;
}
static class ArgsAcceptor {
private static final Logger log = LoggerFactory.getLogger(ArgsAcceptor.class);
private final List<String> arguments = new ArrayList<String>();
private final FlagIndex flags;
private final BasicFlag typeConverison;
private AcceptorState state;
private Flag lastFlag;
enum AcceptorState {KEY_EXPECTED, VALUE_EXPECTED}
public ArgsAcceptor(@Nonnull FlagIndex flags, @Nonnull BasicFlag typeConversion) {
this.flags = flags;
this.typeConverison = typeConversion;
}
void start() {
state = AcceptorState.KEY_EXPECTED;
}
void key(String key, String original) {
if (state != AcceptorState.KEY_EXPECTED) {
errorFlagHasNoValue();
}
Collection<Flag<?>> flagsByName = flags.byName().get(key);
if (flagsByName.isEmpty() && parseBooleanFlag(key) == false) {
flagsByName = flags.byName().get(key.substring(2));
}
if (flagsByName.size() == 1) {
flag(flagsByName.iterator().next(), key);
} else if (flagsByName.isEmpty()) {
errorUnknownFlag(original);
} else {
errorAmbigousFlag(original, flagsByName);
}
}
private void flag(Flag<?> flag, String key) {
Class<?> flagtype = flag.type();
if (flagtype == Boolean.class) {
((Flag<Boolean>) flag).set(parseBooleanFlag(key));
} else {
this.lastFlag = flag;
state = AcceptorState.VALUE_EXPECTED;
}
}
void value(String value) {
//TODO yin: Add support for multi value options and positional arguments
if (state == AcceptorState.VALUE_EXPECTED) {
Class<?> type = lastFlag.type();
BasicFlag.Conversion<?> conversion = typeConverison.forType(type);
if (conversion != null) {
lastFlag.set(conversion.apply(value));
} else {
throw new UnsupportedOperationException(
String.format("Type conversion for Flag<%s>s is registered, Flag: %s",
type.getCanonicalName(), lastFlag.flagID().toString()));
}
state = AcceptorState.KEY_EXPECTED;
} else {
arguments.add(value);
}
}
public List<String> end() {
if (state != AcceptorState.KEY_EXPECTED) {
errorFlagHasNoValue();
}
return arguments;
}
private boolean parseBooleanFlag(String key) {
return key.startsWith("no");
}
private void errorUnknownFlag(String flag) {
log.error("Unknown flag: {}", flag);
}
private void errorAmbigousFlag(String flag, Collection<Flag<?>> flagsByName) {
log.error("Flag {} resolves in multiple classes: {}" , flag, flagsByName);
}
private void errorFlagHasNoValue() {
log.error("Option {} has no value", lastFlag);
}
}
}