com.avaje.ebeaninternal.server.querydefn.OrmQueryDetailParser Maven / Gradle / Ivy
package com.avaje.ebeaninternal.server.querydefn;
import javax.persistence.PersistenceException;
/**
* Parses a Object relational query statement into a OrmQueryDetail and OrmQueryAttributes.
*
* The reason they are split into detail and attributes is that the AutoTune feature is used to
* replace the OrmQueryDetail leaving the attributes unchanged.
*
*/
public class OrmQueryDetailParser {
private final OrmQueryDetail detail = new OrmQueryDetail();
private int maxRows;
private int firstRow;
private String rawWhereClause;
private String rawOrderBy;
private final SimpleTextParser parser;
public OrmQueryDetailParser(String oql) {
this.parser = new SimpleTextParser(oql);
}
public OrmQueryDetail parse() throws PersistenceException {
if (parser.isEmpty()) return detail;
parser.nextWord();
processInitial();
return detail;
}
private void processInitial() {
if (parser.isMatch("select")) {
readSelect();
} else if (parser.isMatch("find")) {
OrmQueryProperties props = readFindFetch();
detail.setBase(props);
} else {
process();
}
while (!parser.isFinished()) {
process();
}
}
private boolean isFetch() {
return parser.isMatch("fetch") || parser.isMatch("join");
}
private void process() {
if (isFetch()) {
detail.fetch(readFindFetch());
} else if (parser.isMatch("where")) {
readWhere();
} else if (parser.isMatch("order", "by")) {
readOrderBy();
} else if (parser.isMatch("limit")) {
readLimit();
} else {
throw new PersistenceException("Query expected 'fetch', 'where','order by' or 'limit' keyword but got ["
+ parser.getWord() + "] \r " + parser.getOql());
}
}
private void readLimit() {
try {
String maxLimit = parser.nextWord();
maxRows = Integer.parseInt(maxLimit);
String offsetKeyword = parser.nextWord();
if (offsetKeyword != null) {
if (!parser.isMatch("offset")) {
throw new PersistenceException("expected offset keyword but got " + parser.getWord());
}
String firstRowLimit = parser.nextWord();
firstRow = Integer.parseInt(firstRowLimit);
parser.nextWord();
}
} catch (NumberFormatException e) {
String msg = "Expected an integer for maxRows or firstRows in limit offset clause";
throw new PersistenceException(msg, e);
}
}
private void readOrderBy() {
// read the by
parser.nextWord();
StringBuilder sb = new StringBuilder();
while (parser.nextWord() != null) {
if (parser.isMatch("limit")) {
break;
} else {
String w = parser.getWord();
if (!w.startsWith("(")) {
sb.append(" ");
}
sb.append(w);
}
}
rawOrderBy = sb.toString().trim();
if (!parser.isFinished()) {
readLimit();
}
}
private void readWhere() {
int nextMode = 0;
StringBuilder sb = new StringBuilder();
while ((parser.nextWord()) != null) {
if (parser.isMatch("order", "by")) {
nextMode = 1;
break;
} else if (parser.isMatch("limit")) {
nextMode = 2;
break;
} else {
sb.append(" ").append(parser.getWord());
}
}
String whereClause = sb.toString().trim();
if (!whereClause.isEmpty()) {
rawWhereClause = whereClause;
}
if (nextMode == 1) {
readOrderBy();
} else if (nextMode == 2) {
readLimit();
}
}
private void readSelect() {
String props = parser.nextWord();
if (props.startsWith("(")) {
props = props.substring(1, props.length() - 1);
OrmQueryProperties base = new OrmQueryProperties(null, props);
detail.setBase(base);
parser.nextWord();
} else {
process();
}
}
private OrmQueryProperties readFindFetch() {
boolean readAlias = false;
String props = null;
String path = parser.nextWord();
String token;
while ((token = parser.nextWord()) != null) {
if (!readAlias && parser.isMatch("as")) {
// next token is alias
parser.nextWord();
readAlias = true;
} else if ('(' == token.charAt(0)) {
props = token;
parser.nextWord();
break;
} else if (isFindFetchEnd()) {
break;
} else if (!readAlias) {
readAlias = true;
} else {
throw new PersistenceException("Expected (props) or new 'fetch' 'where' but got " + token);
}
}
if (props != null) {
props = props.substring(1, props.length() - 1);
}
return new OrmQueryProperties(path, props);
}
private boolean isFindFetchEnd() {
return isFetch() || parser.isMatch("where") || parser.isMatch("order", "by");
}
}