water.util.RString Maven / Gradle / Ivy
package water.util;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.*;
import java.util.Map.Entry;
import water.Key;
import water.H2O;
/**
* A replaceable string that allows very easy and simple replacements.
*
* %placeholder is normally inserted
*
* %$placeholder is inserted in URL encoding for UTF-8 charset. This should be
* used for all hrefs.
*
*/
public class RString {
// A placeholder information with replcement group and start and end labels.
private static class Placeholder {
LabelledStringList.Label start;
LabelledStringList.Label end;
RString group;
// Creates new placeholder
private Placeholder(LabelledStringList.Label start, LabelledStringList.Label end) {
this.start = start;
this.end = end;
this.group = null;
}
// Creates new placeholder for replacement group
private Placeholder(LabelledStringList.Label start, LabelledStringList.Label end, String from) {
this.start = start;
this.end = end;
this.group = new RString(from, this);
}
}
// Placeholders
MMHashMap _placeholders;
// Parts of the final string (replacements and originals together).
LabelledStringList _parts;
// Parent placeholder if the RString is a replacement group.
Placeholder _parent;
// Passes only valid placeholder name characters
static private boolean isIdentChar(char x) {
return (x == '$') || ((x >= 'a') && (x <= 'z')) || ((x >= 'A') && (x <= 'Z')) || ((x >= '0') && (x <= '9')) || (x == '_');
}
// Creates a string that is itself a replacement group.
private RString(final String from, Placeholder parent) {
this(from);
_parent = parent;
}
// Creates the RString from given normal string. The placeholders must begin
// with % sign and if the placeholder name is followed by { }, the placeholder
// is treated as a replacement group. Replacement groups cannot be tested.
// Only letters, numbers and underscore can form a placeholder name. In the
// constructor the string is parsed into parts and placeholders so that all
// replacements in the future are very quick (hashmap lookup in fact).
public RString(final String from) {
_parts = new LabelledStringList();
_placeholders = new MMHashMap<>();
LabelledStringList.Label cur = _parts.begin();
int start = 0;
int end = 0;
while( true ) {
start = from.indexOf("%", end);
if( start == -1 ) {
cur.insertAndAdvance(from.substring(end, from.length()));
break;
}
++start;
if( start == from.length() ) {
throw new ArrayIndexOutOfBoundsException();
}
if( from.charAt(start) == '%' ) {
cur.insertAndAdvance(from.substring(end, start));
end = start + 1;
} else {
cur.insertAndAdvance(from.substring(end, start - 1));
end = start;
while( (end < from.length()) && (isIdentChar(from.charAt(end))) ) {
++end;
}
String pname = from.substring(start, end);
if( (end == from.length()) || (from.charAt(end) != '{') ) {
// it is a normal placeholder
_placeholders.put2(pname, new Placeholder(cur.clone(), cur.clone()));
} else {
// it is another RString
start = end + 1;
end = from.indexOf("}", end);
if( end == -1 ) {
throw new ArrayIndexOutOfBoundsException("Missing } after replacement group");
}
_placeholders.put2(pname, new Placeholder(cur.clone(), cur.clone(), from.substring(start, end)));
++end;
}
}
}
}
// Returns the string with all replaced material.
@Override public String toString() { return _parts.toString(); }
// Removes all replacements from the string (keeps the placeholders so that
// they can be used again.
private void clear() {
//for( Placeholder p : _placeholders.values() ) {
// p.start.removeTill(p.end);
//}
throw H2O.unimpl();
}
public void replace(String what, Key key) {
replace(what, key.user_allowed() ? key.toString() : ""+key.toString()+"");
}
// Replaces the given placeholder with an object. On a single placeholder,
// multiple replaces can be called in which case they are appended one after
// another in order.
public void replace(String what, Object with) {
if (what.charAt(0)=='$')
throw new RuntimeException("$ is now control char that denotes URL encoding!");
for (Placeholder p : _placeholders.get(what))
p.end.insertAndAdvance(with.toString());
ArrayList ar = _placeholders.get("$"+what);
if( ar == null ) return;
for (Placeholder p : ar)
try {
p.end.insertAndAdvance(URLEncoder.encode(with.toString(),"UTF-8"));
} catch (IOException e) {
p.end.insertAndAdvance(e.toString());
}
}
// Returns a replacement group of the given name and clears it so that it
// can be filled again.
private RString restartGroup(String what) {
List all = _placeholders.get(what);
assert all.size() == 1;
Placeholder result = all.get(0);
if( result.group == null ) {
throw new NoSuchElementException("Element " + what + " is not a group.");
}
result.group.clear();
return result.group;
}
// If the RString itself is a replacement group, adds its contents to the
// placeholder.
private void append() {
if( _parent == null ) {
throw new UnsupportedOperationException("Cannot append if no parent is specified.");
}
_parent.end.insertAndAdvance(toString());
}
private static class MMHashMap extends HashMap> {
void put2( K key, V val ) {
ArrayList ar = get(key);
if( ar==null ) put(key,ar = new ArrayList<>());
ar.add(val);
}
}
}
/**
* List that has labels to it (something like copyable iterators) and some very
* basic functionality for it.
*
* Since it is not a private class only the things we require are filled in. The
* labels do not expect or deal with improper use, so make sure you know what
* you are doing when using directly this class.
*/
class LabelledStringList {
// Inner item of the list, single linked
private static class Item {
String value;
Item next;
Item(String value, Item next) {
this.value = value;
this.next = next;
}
}
// Label to the list, which acts as a restricted form of an iterator. Notably
// a label can be used to add items in the middle of the list and also to
// delete all items in between two labels.
class Label {
// element before the label
Item _prev;
// Creates the label from given inner list item so that the label points
// right after it. If null, label points at the very beginnig of the list.
Label(Item prev) {
_prev = prev;
}
// Creates a new copy of the label that points to the same place
@Override protected Label clone() {
return new Label(_prev);
}
// Inserts new string after the label
private void insert(String value) {
if( _prev == null ) {
_begin = new Item(value, _begin);
} else {
_prev.next = new Item(value, _prev.next);
}
++_noOfElements;
_length += value.length();
}
// Inserts new string after the label and then advances the label. Thus in
// theory inserting before the label.
void insertAndAdvance(String value) {
insert(value);
if( _prev == null ) {
_prev = _begin;
} else {
_prev = _prev.next;
}
}
// Removes the element after the label.
private void remove() throws NoSuchElementException {
if( _prev == null ) {
if( _begin == null ) {
throw new NoSuchElementException();
}
_length -= _begin.value.length();
_begin = _begin.next;
} else {
if( _prev.next == null ) {
throw new NoSuchElementException();
}
_length -= _prev.next.value.length();
_prev.next = _prev.next.next;
}
--_noOfElements;
}
// Removes all elements between the label and the other label. The other
// label must come after the first label, otherwise everything after the
// label will be deleted.
private void removeTill(Label other) {
if( _prev == null ) {
if( other._prev == null ) {
return;
}
while( ((_begin != null) && (_begin.next != other._prev.next)) ) {
_length -= _begin.value.length();
_begin = _begin.next;
--_noOfElements;
}
} else {
if( other._prev == null ) {
clear();
_prev = null;
} else {
Item end = other._prev.next;
while( (_prev.next != null) && (_prev.next != end) ) {
remove();
}
}
}
other._prev = _prev;
}
}
// first item
private Item _begin;
// length in characters of the total stored string
private int _length;
// number of String elemets stored
private int _noOfElements;
// Creates an empty string list
LabelledStringList() {
_length = 0;
_noOfElements = 0;
}
// Returns a label to the first item
Label begin() {
return new Label(null);
}
// Returns the number of elements stored in the list
private int length() {
return _noOfElements;
}
// Clears all elements in the list (all labels should be cleared by the
// user when calling this method).
private void clear() {
_begin = null;
_length = 0;
_noOfElements = 0;
}
// Concatenates all parts of the string and returns them as single string
@Override public String toString() {
StringBuilder s = new StringBuilder(_length);
Item i = _begin;
while( i != null ) {
s.append(i.value);
i = i.next;
}
return s.toString();
}
}
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