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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.yql;
import com.yahoo.prelude.query.WeightedSetItem;
import java.util.Arrays;
/**
* Parser of parameter lists on the form {key:value, key:value} or [[key,value], [key,value], ...]
*
* @author bratseth
*/
class ParameterListParser {
public static void addItemsFromString(String string, WeightedSetItem out) {
var s = new ParsableString(string);
switch (s.peek()) {
case '[' : addArrayItems(s, out); break;
case '{' : addMapItems(s, out); break;
default : throw new IllegalArgumentException("Expected a string starting by '[' or '{', " +
"but was '" + s.peek() + "'");
}
}
private static void addArrayItems(ParsableString s, WeightedSetItem out) {
s.pass('[');
while (s.peek() != ']') {
s.pass('[');
long key = s.longTo(s.position(','));
s.pass(',');
int value = s.intTo(s.position(']'));
s.pass(']');
out.addToken(key, value);
s.passOptional(',');
if (s.atEnd()) throw new IllegalArgumentException("Expected an array ending by ']'");
}
s.pass(']');
}
private static void addMapItems(ParsableString s, WeightedSetItem out) {
s.pass('{');
while (s.peek() != '}') {
String key;
if (s.passOptional('\'')) {
key = s.stringTo(s.position('\''));
s.pass('\'');
}
else if (s.passOptional('"')) {
key = s.stringTo(s.position('"'));
s.pass('"');
}
else {
key = s.stringTo(s.position(':')).trim();
}
s.pass(':');
int value = s.intTo(s.position(',','}'));
out.addToken(key, value);
s.passOptional(',');
if (s.atEnd()) throw new IllegalArgumentException("Expected a map ending by '}'");
}
s.pass('}');
}
private static class ParsableString {
int position = 0;
String s;
ParsableString(String s) {
this.s = s;
}
/**
* Returns the next non-space character or UNASSIGNED if we have reached the end of the string.
* The current position is not changed.
*/
char peek() {
int localPosition = position;
while (localPosition < s.length()) {
char nextChar = s.charAt(localPosition++);
if (!Character.isSpaceChar(nextChar))
return nextChar;
}
return Character.UNASSIGNED;
}
/**
* Verifies that the next non-space character is the given and moves the position past it.
*
* @throws IllegalArgumentException if the next non-space character is not the given character
*/
void pass(char character) {
while (position < s.length()) {
char nextChar = s.charAt(position++);
if (!Character.isSpaceChar(nextChar)) {
if (nextChar == character)
return;
else
throw new IllegalArgumentException("Expected '" + character + "' at position " + (position-1) +
" but got '" + nextChar + "'");
}
}
throw new IllegalArgumentException("Expected '" + character + "' at position " + (position-1) +
" but reached the end");
}
/**
* Checks if the next non-space character is the given and moves the position past it if so.
* Does not change the position otherwise.
*
* @return true if the next non-space character was the given character
*/
boolean passOptional(char character) {
int localPosition = position;
while (localPosition < s.length()) {
char nextChar = s.charAt(localPosition++);
if (!Character.isSpaceChar(nextChar)) {
if (nextChar == character) {
position = localPosition;
return true;
} else {
return false;
}
}
}
return false;
}
/**
* Returns the position of the next occurrence of any of the given characters.
*
* @throws IllegalArgumentException if there are no further occurrences of any of the given characters
*/
int position(char ... characters) {
int localPosition = position;
while (localPosition < s.length()) {
char nextChar = s.charAt(localPosition);
for (char character : characters)
if (nextChar == character) return localPosition;
localPosition++;
}
throw new IllegalArgumentException("Expected one of " + Arrays.toString(characters) + " after " + position);
}
boolean atEnd() {
return position >= s.length();
}
/**
* Returns the string value from the current to the given position, and moves the current
* position to the next character.
*
* @throws IllegalArgumentException if end is beyond the last position of the string
*/
String stringTo(int end) {
try {
String value = s.substring(position, end);
position = end;
return value;
}
catch (IndexOutOfBoundsException e) {
throw new IllegalArgumentException(end + " is larger than the size of the string, " + s.length());
}
}
/**
* Returns the int value from the current to the given position, and moves the current
* position to the next character.
*
* @throws IllegalArgumentException if the string cannot be parsed to an int or end is larger than the string
*/
int intTo(int end) {
int start = position;
String value = stringTo(end);
try {
return Integer.parseInt(value.trim());
}
catch (NumberFormatException e) {
throw new IllegalArgumentException("Expected an integer between positions " + start + " and " + end +
", but got " + value);
}
}
/**
* Returns the long value from the current to the given position, and moves the current
* position to the next character.
*
* @throws IllegalArgumentException if the string cannot be parsed to a long or end is larger than the string
*/
long longTo(int end) {
int start = position;
String value = stringTo(end);
try {
return Long.parseLong(value.trim());
}
catch (NumberFormatException e) {
throw new IllegalArgumentException("Expected an integer between positions " + start + " and " + end +
", but got " + value);
}
}
}
}
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