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Copy pathGflagsParser.java
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157 lines (137 loc) · 4.72 KB
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package com.github.yin.flags;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.annotations.VisibleForTesting;
import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
/**
* Parses command-line arguments under rules defined by:
* https://gflags.github.io/gflags/
*/
//TODO yin: Make this modular, refactor out a layered Acceptor schema
class GflagsParser implements Parser<String[]> {
private static final Logger log = LoggerFactory.getLogger(GflagsParser.class);
private final List<String> arguments = new ArrayList<String>();
private final FlagIndex<FlagMetadata> flags;
private AcceptorState state;
private FlagMetadata lastMeta;
enum AcceptorState {KEY_EXPECTED, VALUE_EXPECTED}
public GflagsParser(@Nonnull FlagIndex<FlagMetadata> flags) {
this.flags = flags;
}
@Override
public List<String> parse(String[] args) {
start();
for (String arg : args) {
next(arg);
}
return end();
}
protected void start() {
state = AcceptorState.KEY_EXPECTED;
}
protected void next(String arg) {
if (arg.startsWith("--")) {
flag(arg.substring(2), arg);
} else if (arg.startsWith("-")) {
flag(arg.substring(1), arg);
} else {
handleValue(arg);
}
}
protected void flag(String flag, String orig) {
String[] tokens = flag.split("=", 2);
if (tokens.length == 1) {
key(flag, orig);
} else {
String key = tokens[0];
String value = tokens[1];
keyAndValue(key, value, orig);
}
}
protected void key(String key, String original) {
if (state != AcceptorState.KEY_EXPECTED) {
errorFlagHasNoValue();
}
Collection<FlagMetadata> flagsByName = flags.byName().get(key);
if (flagsByName.isEmpty() && key.startsWith("no")) {
flagsByName = flags.byName().get(key.substring(2));
if (flagsByName.size() == 1) {
handleFalseFlag(flagsByName.iterator().next(), original);
} else if (flagsByName.isEmpty()) {
errorUnknownFlag(original);
} else {
errorAmbigousFlag(original, flagsByName);
}
}
if (flagsByName.size() == 1) {
handleFlag(flagsByName.iterator().next());
} else if (flagsByName.isEmpty()) {
errorUnknownFlag(original);
} else {
errorAmbigousFlag(original, flagsByName);
}
}
protected void keyAndValue(String key, String value, String original) {
if (state != AcceptorState.KEY_EXPECTED) {
errorFlagHasNoValue();
}
Collection<FlagMetadata> flagsByName = flags.byName().get(key);
if (flagsByName.size() == 1) {
handleFlag(flagsByName.iterator().next());
handleValue(value);
} else if (flagsByName.isEmpty()) {
errorUnknownFlag(original);
} else {
errorAmbigousFlag(original, flagsByName);
}
}
protected void handleFlag(FlagMetadata meta) {
Class<?> flagtype = meta.getClass();
if (BasicFlag.BooleanFlag.class.isAssignableFrom(flagtype)) {
meta.flag().parse("true");
} else {
this.lastMeta = meta;
state = AcceptorState.VALUE_EXPECTED;
}
}
protected void handleFalseFlag(FlagMetadata meta, String orig) {
Class<?> flagtype = meta.getClass();
if (BasicFlag.BooleanFlag.class.isAssignableFrom(flagtype)) {
meta.flag().parse("false");
} else {
errorUnknownFlag(orig);
}
}
protected void handleValue(String value) {
//TODO yin: Add support for collections
if (state == AcceptorState.VALUE_EXPECTED) {
lastMeta.flag().parse(value);
state = AcceptorState.KEY_EXPECTED;
} else {
arguments.add(value);
}
}
protected List<String> end() {
if (state != AcceptorState.KEY_EXPECTED) {
errorFlagHasNoValue();
}
return arguments;
}
protected void errorUnknownFlag(String flag) {
log.error("Unknown flag: {}", flag);
}
protected void errorAmbigousFlag(String flag, Collection<FlagMetadata> flagsByName) {
log.error("Flag {} resolves in multiple classes: {}", flag,
flagsByName.stream().map(meta -> meta.flagID()).toArray());
}
protected void errorFlagHasNoValue() {
log.error("Option {} has no value", lastMeta);
}
@VisibleForTesting
void setState(AcceptorState state) {
this.state = state;
}
}