jsquery_io.c

/*-------------------------------------------------------------------------
 *
 * jsquery_io.c
 *     I/O functions for jsquery datatype
 *
 * Copyright (c) 2014, PostgreSQL Global Development Group
 * Author: Teodor Sigaev <teodor@sigaev.ru>
 *
 * IDENTIFICATION
 *    contrib/jsquery/jsquery_io.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"
#include "miscadmin.h"
#include "lib/stringinfo.h"
#include "utils/builtins.h"
#include "utils/json.h"

#include "jsquery.h"

PG_MODULE_MAGIC;

void
alignStringInfoInt(StringInfo buf)
{
	switch(INTALIGN(buf->len) - buf->len)
	{
		case 3:
			appendStringInfoCharMacro(buf, 0);
		case 2:
			appendStringInfoCharMacro(buf, 0);
		case 1:
			appendStringInfoCharMacro(buf, 0);
		default:
			break;
	}
}

static int
flattenJsQueryItem(StringInfo buf, JsQueryItem *item)
{
	int32	pos = buf->len - VARHDRSZ; /* position from begining of jsquery data */
	int32	chld, next;

	check_stack_depth();

	appendStringInfoChar(buf, (char)item->type);
	alignStringInfoInt(buf);

	next = (item->next) ? buf->len : 0;
	appendBinaryStringInfo(buf, (char*)&next /* fake value */, sizeof(next));

	switch(item->type)
	{
		case jqiKey:
		case jqiString:
			appendBinaryStringInfo(buf, (char*)&item->string.len, sizeof(item->string.len));
			appendBinaryStringInfo(buf, item->string.val, item->string.len);
			appendStringInfoChar(buf, '\0');
			break;
		case jqiNumeric:
			appendBinaryStringInfo(buf, (char*)item->numeric, VARSIZE(item->numeric));
			break;
		case jqiBool:
			appendBinaryStringInfo(buf, (char*)&item->boolean, sizeof(item->boolean));
			break;
		case jqiArray:
			{
				int32	i, arrayStart;

				appendBinaryStringInfo(buf, (char*)&item->array.nelems, sizeof(item->array.nelems));
				arrayStart = buf->len;

				/* reserve place for "pointers" to array's elements */
				for(i=0; i<item->array.nelems; i++)
					appendBinaryStringInfo(buf, (char*)&i /* fake value */, sizeof(i));

				for(i=0; i<item->array.nelems; i++)
				{
					chld = flattenJsQueryItem(buf, item->array.elems[i]);
					*(int32*)(buf->data + arrayStart + i * sizeof(i)) = chld;
				}

			}
			break;
		case jqiAnd:
		case jqiOr:
			{
				int32	left, right;

				left = buf->len;
				appendBinaryStringInfo(buf, (char*)&left /* fake value */, sizeof(left));
				right = buf->len;
				appendBinaryStringInfo(buf, (char*)&right /* fake value */, sizeof(right));

				chld = flattenJsQueryItem(buf, item->args.left);
				*(int32*)(buf->data + left) = chld;
				chld = flattenJsQueryItem(buf, item->args.right);
				*(int32*)(buf->data + right) = chld;
			}
			break;
		case jqiEqual:
		case jqiIn:
		case jqiLess:
		case jqiGreater:
		case jqiLessOrEqual:
		case jqiGreaterOrEqual:
		case jqiContains:
		case jqiContained:
		case jqiOverlap:
		case jqiNot:
			{
				int32 arg;

				arg = buf->len;
				appendBinaryStringInfo(buf, (char*)&arg /* fake value */, sizeof(arg));

				chld = flattenJsQueryItem(buf, item->arg);
				*(int32*)(buf->data + arg) = chld;
			}
			break;
		case jqiNull:
		case jqiCurrent:
		case jqiAny:
		case jqiAnyArray:
			break;
		default:
			elog(ERROR, "Unknown JsQueryItem type: %d", item->type);
	}

	if (item->next)
		*(int32*)(buf->data + next) = flattenJsQueryItem(buf, item->next);

	return  pos;
}

PG_FUNCTION_INFO_V1(jsquery_in);
Datum
jsquery_in(PG_FUNCTION_ARGS)
{
	char			*in = PG_GETARG_CSTRING(0);
	int32			len = strlen(in);
	JsQueryItem		*jsquery = parsejsquery(in, len);
	JsQuery			*res;
	StringInfoData	buf;

	initStringInfo(&buf);
	enlargeStringInfo(&buf, 4 * len /* estimation */); 

	appendStringInfoSpaces(&buf, VARHDRSZ);

	if (jsquery != NULL)
	{
		flattenJsQueryItem(&buf, jsquery);

		res = (JsQuery*)buf.data;
		SET_VARSIZE(res, buf.len);

		PG_RETURN_JSQUERY(res);
	}

	PG_RETURN_NULL();
}

int32
readJsQueryHeader(char *base, int32 pos, int32 *type, int32 *nextPos)
{
	read_byte(*type, base, pos);
	switch(INTALIGN(pos) - pos)
	{
		case 3: pos++;
		case 2: pos++;
		case 1: pos++;
		default: break;
	}
	read_int32(*nextPos, base, pos);

	return pos;
}


static void
printOperation(StringInfo buf, int type)
{
	switch(type)
	{
		case jqiAnd:
			appendBinaryStringInfo(buf, " & ", 3); break;
		case jqiOr:
			appendBinaryStringInfo(buf, " | ", 3); break;
		case jqiEqual:
			appendBinaryStringInfo(buf, " = ", 3); break;
		case jqiLess:
			appendBinaryStringInfo(buf, " < ", 3); break;
		case jqiGreater:
			appendBinaryStringInfo(buf, " > ", 3); break;
		case jqiLessOrEqual:
			appendBinaryStringInfo(buf, " <= ", 4); break;
		case jqiGreaterOrEqual:
			appendBinaryStringInfo(buf, " >= ", 4); break;
		case jqiContains:
			appendBinaryStringInfo(buf, " @> ", 4); break;
		case jqiContained:
			appendBinaryStringInfo(buf, " <@ ", 4); break;
		case jqiOverlap:
			appendBinaryStringInfo(buf, " && ", 4); break;
		default:
			elog(ERROR, "Unknown JsQueryItem type: %d", type);
	}
}

static void
printJsQueryItem(StringInfo buf, char *base, int32 pos, bool inKey, bool printBracketes)
{
	int32		type;
	int32		nextPos;

	check_stack_depth();

	pos = readJsQueryHeader(base, pos, &type, &nextPos);

	switch(type)
	{
		case jqiNull:
			appendStringInfoString(buf, "null");
			break;
		case jqiKey:
		case jqiString:
			{
				int32 len;

				read_int32(len, base, pos);
				if (inKey && type == jqiKey)
					appendStringInfoChar(buf, '.');
				escape_json(buf, base + pos);
				pos += len + 1;
			}
			break;
		case jqiNumeric:
			{
				Numeric	n = (Numeric)(base + pos);

				pos += VARSIZE(n);

				appendStringInfoString(buf,
										DatumGetCString(DirectFunctionCall1(numeric_out,
											PointerGetDatum(n))));
			}
			break;
		case jqiBool:
			{
				bool	v;

				read_byte(v, base, pos);

				if (v)
					appendBinaryStringInfo(buf, "true", 4);
				else
					appendBinaryStringInfo(buf, "false", 5);
			}
			break;
		case jqiArray:
			{
				int32	i, nelems, *arrayPos;

				read_int32(nelems, base, pos);
				arrayPos = (int32*)(base + pos);
				pos += nelems * sizeof(*arrayPos);

				if (printBracketes)
					appendStringInfoChar(buf, '['); 

				for(i=0; i<nelems; i++)
				{
					if (i != 0)
						appendBinaryStringInfo(buf, ", ", 2);

					printJsQueryItem(buf, base, arrayPos[i], false, true);
				}

				if (printBracketes)
					appendStringInfoChar(buf, ']');
			}
			break;
		case jqiAnd:
		case jqiOr:
			{
				int32	left, right;

				read_int32(left, base, pos);
				read_int32(right, base, pos);

				appendStringInfoChar(buf, '(');
				printJsQueryItem(buf, base, left, false, true);
				printOperation(buf, type);
				printJsQueryItem(buf, base, right, false, true);
				appendStringInfoChar(buf, ')');
			}
			break;
		case jqiEqual:
		case jqiLess:
		case jqiGreater:
		case jqiLessOrEqual:
		case jqiGreaterOrEqual:
		case jqiContains:
		case jqiContained:
		case jqiOverlap:
			{
				int32 arg;

				read_int32(arg, base, pos);

				printOperation(buf, type);
				printJsQueryItem(buf, base, arg, false, true);
			}
			break;
		case jqiIn:
			{
				int32 arg;

				read_int32(arg, base, pos);

				appendBinaryStringInfo(buf, " IN (", 5);
				printJsQueryItem(buf, base, arg, false, false);
				appendStringInfoChar(buf, ')');
			}
			break;
		case jqiNot:
			{
				int32 arg;

				read_int32(arg, base, pos);

				appendBinaryStringInfo(buf, "!(", 2);
				printJsQueryItem(buf, base, arg, false, true);
				appendStringInfoChar(buf, ')');
			}
			break;
		case jqiAny:
			if (inKey)
				appendStringInfoChar(buf, '.');
			appendStringInfoChar(buf, '*');
			break;
		case jqiCurrent:
			if (inKey)
				appendStringInfoChar(buf, '.');
			appendStringInfoChar(buf, '$');
			break;
		case jqiAnyArray:
			if (inKey)
				appendStringInfoChar(buf, '.');
			appendStringInfoChar(buf, '#');
			break;
		default:
			elog(ERROR, "Unknown JsQueryItem type: %d", type);
	}

	if (nextPos > 0)
		printJsQueryItem(buf, base, nextPos, true, true);
}

PG_FUNCTION_INFO_V1(jsquery_out);
Datum
jsquery_out(PG_FUNCTION_ARGS)
{
	JsQuery			*in = PG_GETARG_JSQUERY(0);
	StringInfoData	buf;

	initStringInfo(&buf);
	enlargeStringInfo(&buf, VARSIZE(in) /* estimation */); 

	printJsQueryItem(&buf, VARDATA(in), 0, false, true);

	PG_RETURN_CSTRING(buf.data);
}