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/* Copyright (c) 2013-2020 VMware, Inc. or its affiliates. All rights reserved. */
package com.rabbitmq.jms.parse.sql;
import java.util.List;
import com.rabbitmq.jms.parse.Visitor;
/**
* This visitor accumulates a compiled version of the tree (code) in the form of an Erlang term.
* It visits the tree node (parent) both before and after the subtree nodes (children), so as to
* bracket the generated code correctly.
*/
class SqlCompilerVisitor implements Visitor {
private static final boolean BEFORE = true;
private static final boolean AFTER = false;
private final StringBuilder sb = new StringBuilder();
@Override
public boolean visitBefore(SqlTreeNode parent, SqlTreeNode[] children) {
codeOf(BEFORE, this.sb, parent, children);
return true; // traverse the whole tree
}
@Override
public boolean visitAfter(SqlTreeNode parent, SqlTreeNode[] children) {
codeOf(AFTER, this.sb, parent, children);
return true; // traverse the whole tree
}
public String extractCode() {
if (this.sb.length() == 0) return ""; // nothing to extract
// a leading comma is removed
return this.sb.substring((this.sb.charAt(0) == ',') ? 1 : 0);
}
/**
* Reset code accumulator -- used in unit tests
*/
void clearCode() {
this.sb.setLength(0);
}
/**
* @param before - true when this is called before the children are called (prefix), false when this is called after the children are called (postfix).
* @param sb - accumulates the code expression
* @param parent - the parent node
* @param children - the array of children nodes
*/
private static final void codeOf(boolean before, StringBuilder sb, SqlTreeNode parent, SqlTreeNode[] children) {
switch(parent.treeType()) {
case CONJUNCTION:
if (before) sb.append(",{").append(atomString(SqlTokenType.AND.opCode()));
else sb.append('}');
break;
case DISJUNCTION:
if (before) sb.append(",{").append(atomString(SqlTokenType.OR.opCode()));
else sb.append('}');
break;
case LEAF:
switch(parent.value().type()) {
case FALSE:
case TRUE:
if (before) sb.append(',').append(atomString(parent.value().type().opCode()));
break;
case FLOAT:
if (before) sb.append(',').append(parent.value().getFloat());
break;
case HEX:
if (before) sb.append(',').append(parent.value().getHex());
break;
case IDENT:
if (before) sb.append(',').append(identString(parent.value().getIdent()));
break;
case INT:
if (before) sb.append(',').append(parent.value().getLong());
break;
case LIST:
if (before) sb.append(',').append(stringListString(parent.value().getList()));
break;
case STRING:
if (before) sb.append(',').append(binString(parent.value().getString()));
break;
default:
throw new RuntimeException(String.format( "Cannot compile tree type: [%s] with token [%s]."
, parent.treeType(), parent.value()
));
}
break;
case LIST:
if (before) sb.append(',').append(stringListString(parent.value().getList()));
break;
case PATTERN1:
if (before) ;
else sb.append(',').append(atomString("no_escape"));
break;
case PATTERN2:
break; // only a list of arguments is required
case POSTFIXUNARYOP:
case PREFIXUNARYOP:
case TERNARYOP:
case BINARYOP:
switch (parent.value().type()) {
case BETWEEN:
case NOT:
case NOT_BETWEEN:
case NOT_NULL:
case NULL:
case OP_MINUS:
case OP_PLUS:
case CMP_EQ:
case CMP_GT:
case CMP_GTEQ:
case CMP_LT:
case CMP_LTEQ:
case CMP_NEQ:
case IN:
case LIKE:
case NOT_IN:
case NOT_LIKE:
case OP_DIV:
case OP_MULT:
if (before) sb.append(",{").append(atomString(parent.value().type().opCode()));
else sb.append('}');
break;
default:
throw new RuntimeException(String.format( "Internal error: cannot compile tree type: [%s] with token [%s]."
, parent.treeType(), parent.value()
));
}
break;
default:
throw new RuntimeException(String.format( "Internal error: cannot compile tree type: [%s]."
, parent.treeType()
));
}
}
private static StringBuilder atomString(String str) {
return new StringBuilder().append('\'').append(str).append('\'');
}
private static StringBuilder prepend(Obj obj, StringBuilder sb) {
return sb.insert(0, obj);
}
private static StringBuilder identString(String identName) {
return prepend('{', atomString("ident")).append(',').append(binString(identName)).append('}');
}
/**
* Produce Erlang list of binary string literals from list.
* @param list - list of strings to convert
* @return string whose contents is an Erlang expression denoting a list of binary string literals
*/
private static StringBuilder stringListString(List list) {
if (list.size() == 0) return new StringBuilder("[]");
StringBuilder sb = new StringBuilder();
for(String s : list) {
sb.append(',').append(binString(s));
}
return sb.replace(0, 1, "[").append(']');
}
/**
* Produce Erlang binary string literal from str. Result is ‘<<"str">>’
* but with ‘"’s and ‘\’s in str backslash escaped.
* @param str - string to convert to literal
* @return string whose contents is an Erlang expression denoting a binary string literal
*/
private static StringBuilder binString(String str) {
StringBuilder sb = new StringBuilder("<<\"");
for(char c : str.toCharArray()) {
if (c == '"' || c == '\\') sb.append('\\');
sb.append(c);
}
return sb.append("\">>");
}
}
