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#1150 - Refactor convert RawSql and RawSqlBuilder into interfaces and push the parsers into io.ebeaninternal
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rob bygrave
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package io.ebeaninternal.server.rawsql;
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import io.ebeaninternal.server.rawsql.SpiRawSql.Sql;
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import io.ebeaninternal.server.querydefn.SimpleTextParser;
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/**
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* Parses sql-select queries to try and determine the location where WHERE and
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* HAVING clauses can be added dynamically to the sql.
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*/
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class DRawSqlParser {
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private static final String $_AND_HAVING = "${andHaving}";
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private static final String $_HAVING = "${having}";
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private static final String $_AND_WHERE = "${andWhere}";
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private static final String $_WHERE = "${where}";
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private final SimpleTextParser textParser;
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private String sql;
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private int placeHolderWhere;
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private int placeHolderAndWhere;
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private int placeHolderHaving;
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private int placeHolderAndHaving;
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private final boolean hasPlaceHolders;
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private int selectPos = -1;
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private int distinctPos = -1;
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private int fromPos = -1;
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private int wherePos = -1;
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private int groupByPos = -1;
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private int havingPos = -1;
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private int orderByPos = -1;
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private int orderByStmtPos = -1;
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private boolean whereExprAnd;
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private int whereExprPos = -1;
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private boolean havingExprAnd;
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private int havingExprPos = -1;
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public static Sql parse(String sql) {
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return new DRawSqlParser(sql).parse();
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}
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private DRawSqlParser(String sqlString) {
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sqlString = sqlString.trim();
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sqlString = sqlString.replace('\n', ' ');
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this.sql = sqlString;
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this.hasPlaceHolders = findAndRemovePlaceHolders();
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this.textParser = new SimpleTextParser(sqlString);
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}
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private Sql parse() {
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if (!hasPlaceHolders()) {
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// parse the sql for the keywords...
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// select, from, where, having, group by, order by
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parseSqlFindKeywords(true);
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}
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whereExprPos = findWhereExprPosition();
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havingExprPos = findHavingExprPosition();
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String preFrom = removeWhitespace(findPreFromSql());
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String preWhere = removeWhitespace(findPreWhereSql());
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String preHaving = removeWhitespace(findPreHavingSql());
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String orderByPrefix = findOrderByPrefixSql();
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String orderBySql = findOrderBySql();
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preFrom = trimSelectKeyword(preFrom);
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return new Sql(sql, preFrom, preWhere, whereExprAnd, preHaving, havingExprAnd, orderByPrefix, orderBySql, (distinctPos > -1));
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}
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/**
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* Find and remove the known place holders such as ${where}.
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*/
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private boolean findAndRemovePlaceHolders() {
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placeHolderWhere = removePlaceHolder($_WHERE);
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placeHolderAndWhere = removePlaceHolder($_AND_WHERE);
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placeHolderHaving = removePlaceHolder($_HAVING);
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placeHolderAndHaving = removePlaceHolder($_AND_HAVING);
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return hasPlaceHolders();
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}
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private int removePlaceHolder(String placeHolder) {
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int pos = sql.indexOf(placeHolder);
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if (pos > -1) {
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int after = pos + placeHolder.length() + 1;
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if (after > sql.length()) {
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sql = sql.substring(0, pos);
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} else {
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sql = sql.substring(0, pos) + sql.substring(after);
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}
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}
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return pos;
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}
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private boolean hasPlaceHolders() {
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return placeHolderWhere > -1 || placeHolderAndWhere > -1 || placeHolderHaving > -1 || placeHolderAndHaving > -1;
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}
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/**
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* Trim off the select keyword (to support row_number() limit function).
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*/
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private String trimSelectKeyword(String preWhereExprSql) {
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if (selectPos < 0) {
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throw new IllegalStateException("select keyword not found?");
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}
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// trim of select keyword
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preWhereExprSql = preWhereExprSql.trim();
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String select = preWhereExprSql.substring(0, 7);
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if (!select.equalsIgnoreCase("select ")) {
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throw new RuntimeException("Expecting [" + preWhereExprSql + "] to start with \"select\"");
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}
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preWhereExprSql = preWhereExprSql.substring(7).trim();
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if (distinctPos > -1) {
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// trim of distinct keyword
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String distinct = preWhereExprSql.substring(0, 9);
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if (!distinct.equalsIgnoreCase("distinct ")) {
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throw new RuntimeException("Expecting [" + preWhereExprSql + "] to start with \"select distinct\"");
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}
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preWhereExprSql = preWhereExprSql.substring(9);
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}
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return preWhereExprSql;
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}
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private String findOrderByPrefixSql() {
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return (orderByPos < 1) ? null : sql.substring(orderByPos, orderByStmtPos);
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}
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private String findOrderBySql() {
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return (orderByStmtPos < 1) ? null : sql.substring(orderByStmtPos).trim();
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}
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private String findPreHavingSql() {
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if (havingExprPos > whereExprPos) {
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// an order by clause follows...
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return sql.substring(whereExprPos, havingExprPos - 1);
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}
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if (whereExprPos > -1) {
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if (orderByPos == -1) {
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return sql.substring(whereExprPos);
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} else if (whereExprPos == orderByPos) {
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return "";
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} else {
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return sql.substring(whereExprPos, orderByPos - 1);
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}
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}
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return null;
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}
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private String findPreFromSql() {
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return sql.substring(0, fromPos - 1);
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}
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private String findPreWhereSql() {
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if (whereExprPos > -1) {
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return sql.substring(fromPos, whereExprPos - 1);
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} else {
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return sql.substring(fromPos);
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}
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}
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private void parseSqlFindKeywords(boolean allKeywords) {
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selectPos = textParser.findWordLower("select");
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if (selectPos == -1) {
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String msg = "Error parsing sql, can not find SELECT keyword in:";
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throw new RuntimeException(msg + sql);
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}
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String possibleDistinct = textParser.nextWord();
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if ("distinct".equals(possibleDistinct)) {
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distinctPos = textParser.getPos() - 8;
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}
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fromPos = textParser.findWordLower("from");
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if (fromPos == -1) {
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String msg = "Error parsing sql, can not find FROM keyword in:";
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throw new RuntimeException(msg + sql);
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}
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if (!allKeywords) {
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return;
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}
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wherePos = textParser.findWordLower("where");
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if (wherePos == -1) {
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groupByPos = textParser.findWordLower("group", fromPos + 5);
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} else {
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groupByPos = textParser.findWordLower("group");
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}
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if (groupByPos > -1) {
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havingPos = textParser.findWordLower("having");
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}
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int startOrderBy = havingPos;
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if (startOrderBy == -1) {
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startOrderBy = groupByPos;
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}
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if (startOrderBy == -1) {
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startOrderBy = wherePos;
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}
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if (startOrderBy == -1) {
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startOrderBy = fromPos;
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}
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orderByPos = textParser.findWordLower("order", startOrderBy);
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if (orderByPos > 1) {
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// there might be keywords like siblings in between the order
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// and by so search for the by keyword explicitly
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orderByStmtPos = 2 + textParser.findWordLower("by", orderByPos);
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}
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}
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private int findWhereExprPosition() {
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if (hasPlaceHolders) {
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if (placeHolderWhere > -1) {
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return placeHolderWhere;
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} else {
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whereExprAnd = true;
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return placeHolderAndWhere;
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}
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}
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whereExprAnd = wherePos > 0;
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if (groupByPos > 0) {
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return groupByPos;
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}
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if (havingPos > 0) {
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return havingPos;
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}
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if (orderByPos > 0) {
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return orderByPos;
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}
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return -1;
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}
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private int findHavingExprPosition() {
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if (hasPlaceHolders) {
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if (placeHolderHaving > -1) {
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return placeHolderHaving;
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} else {
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havingExprAnd = true;
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return placeHolderAndHaving;
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}
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}
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havingExprAnd = havingPos > 0;
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if (orderByPos > 0) {
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return orderByPos;
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}
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return -1;
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}
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private String removeWhitespace(String sql) {
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if (sql == null) {
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return "";
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}
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boolean removeWhitespace = false;
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int length = sql.length();
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StringBuilder sb = new StringBuilder();
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for (int i = 0; i < length; i++) {
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char c = sql.charAt(i);
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if (removeWhitespace) {
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if (!Character.isWhitespace(c)) {
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sb.append(c);
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removeWhitespace = false;
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}
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} else {
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if (c == '\r' || c == '\n') {
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sb.append('\n');
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removeWhitespace = true;
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} else {
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sb.append(c);
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}
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}
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}
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String s = sb.toString();
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return s.trim();
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}
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}
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