com.viaoa.datasource.query.OAQueryTokenManager Maven / Gradle / Ivy

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/*  Copyright 1999 Vince Via [email protected]
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
package com.viaoa.datasource.query;


/**
 * Used to parse a query into tokens.
 * @author vincevia
 */
public class OAQueryTokenManager {
    String query;
    int len;
    int pos = 0;
    StringBuffer sb;

    public void setQuery(String query) {
        this.query = query;
        len = query.length();
        sb = new StringBuffer(len+32);
        pos = 0;
    }

    public OAQueryToken getNext() {
        OAQueryToken token = new OAQueryToken();
        char charWaitFor = 0;
        char ch=0, chLast;
        if (len > 0) sb.delete(0, len-1);
        boolean bReturn = false;
        String sError = null;

        for ( ; !bReturn && pos') {
                    token.type = OAQueryTokenType.GT;
                }
                else if (ch == '<') {
                    token.type = OAQueryTokenType.LT;
                }
                else if (ch == '=') {
                    token.type = OAQueryTokenType.EQUAL;
                }
                else if (ch == '!') {
                    token.type = OAQueryTokenType.OPERATOR;
                }
                else if (ch == '&') {
                    token.type = OAQueryTokenType.AND;
                }
                else if (ch == '|') {
                    token.type = OAQueryTokenType.OR;
                }
                else if ( (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || ch == '_') {
                    token.type = OAQueryTokenType.VARIABLE;
                }
                else if (ch == '?') {
                    token.type = OAQueryTokenType.QUESTION;
                    bReturn = true;
                }
                else if (ch == ',') {
                    token.type = OAQueryTokenType.COMMA;
                    bReturn = true;
                }
                else {
                    sError = "Illegal token '"+ch+"'";
                    bReturn = true;
                }
            }
            else if (token.type == OAQueryTokenType.VARIABLE) {
                if (ch == '[') {  // check for PASSTHRU
                    if ((new String(sb)).equalsIgnoreCase("PASS")) {
                        token.type = OAQueryTokenType.PASSTHRU;
                        if (len > 0) sb.delete(0, len-1);
                        continue;
                    }
                }
                if ( (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '_' || ch == '.') {
                }
                else {
                    bReturnNow = true;
                }
            }
            else if (token.type == OAQueryTokenType.NUMBER) {
                if (Character.isDigit(ch)) {
                }
                else if (ch == '.') {
                }
                else {
                    bReturnNow = true;
                }
            }
            else if (token.isOperator()) {
                switch (chLast) {
                    case '>':
                        if (ch != '=') {
                            token.type = OAQueryTokenType.GT;
                            bReturnNow = true;
                        }
                        else token.type = OAQueryTokenType.GE;
                        break;
                    case '<':
                        if (ch != '=') {
                            token.type = OAQueryTokenType.LT;
                            bReturnNow = true;
                        }
                        else token.type = OAQueryTokenType.LE;
                        break;
                    case '=':
                        if (ch != '=') {
                            token.type = OAQueryTokenType.EQUAL;
                            bReturnNow = true;
                        }
                        else token.type = OAQueryTokenType.EQUAL;
                        break;
                    case '!':
                        if (ch != '=') sError = "Token '!' not valid without '='";
                        else token.type = OAQueryTokenType.NOTEQUAL;
                        break;
                    case '&':
                        if (ch != '&') {
                            token.type = OAQueryTokenType.AND;
                            bReturnNow = true;
                        }
                        else token.type = OAQueryTokenType.AND;
                        break;
                    case '|':
                        if (ch != '|') {
                            token.type = OAQueryTokenType.OR;
                            bReturnNow = true;
                        }
                        else token.type = OAQueryTokenType.OR;
                        break;
                }
                bReturn = true;
            }
            if (bReturnNow) break; // leave on current pos
            sb.append(ch);
        }
        if (sError != null) throw new RuntimeException(sError + " at position "+pos+" in query " + query);
        token.value = new String(sb);
        if (token.type == 0) token.type = OAQueryTokenType.EOF;
        else if (token.type == OAQueryTokenType.VARIABLE) {
            // if VarName, check for DESC, LIKE, AND, OR
            String s = token.value.toUpperCase();
            if (s.equals("IS")) token.type = OAQueryTokenType.EQUAL;
            else if (s.equals("AND")) token.type = OAQueryTokenType.AND;
            else if (s.equals("OR")) token.type = OAQueryTokenType.OR;
            else if (s.equals("NULL")) token.type = OAQueryTokenType.NULL;
            else if (s.equals("LIKE")) token.type = OAQueryTokenType.LIKE;
            else if (s.equals("NOTLIKE")) token.type = OAQueryTokenType.NOTLIKE;
            else if (s.equals("IN")) token.type = OAQueryTokenType.IN;
        }
        return token;
    }

}