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Initial implementation of the json_mergepatch(A,B) SQL function.

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FossilOrigin-Name: a267444039af519f088dd8f8ee33f686cc3071c087677075af2364ebc2587514
This commit is contained in:
drh
2017-03-22 21:24:31 +00:00
parent 918938f9c2
commit 633647af75
4 changed files with 192 additions and 27 deletions
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138
ext/misc/json1.c
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@ -138,9 +138,10 @@ static const char * const jsonType[] = {
#define JNODE_RAW 0x01 /* Content is raw, not JSON encoded */
#define JNODE_ESCAPE 0x02 /* Content is text with \ escapes */
#define JNODE_REMOVE 0x04 /* Do not output */
#define JNODE_REPLACE 0x08 /* Replace with JsonNode.iVal */
#define JNODE_APPEND 0x10 /* More ARRAY/OBJECT entries at u.iAppend */
#define JNODE_LABEL 0x20 /* Is a label of an object */
#define JNODE_REPLACE 0x08 /* Replace with JsonNode.u.iReplace */
#define JNODE_PATCH 0x10 /* Patch with JsonNode.u.pPatch */
#define JNODE_APPEND 0x20 /* More ARRAY/OBJECT entries at u.iAppend */
#define JNODE_LABEL 0x40 /* Is a label of an object */
/* A single node of parsed JSON
@ -148,12 +149,13 @@ static const char * const jsonType[] = {
struct JsonNode {
u8 eType; /* One of the JSON_ type values */
u8 jnFlags; /* JNODE flags */
u8 iVal; /* Replacement value when JNODE_REPLACE */
u32 n; /* Bytes of content, or number of sub-nodes */
union {
const char *zJContent; /* Content for INT, REAL, and STRING */
u32 iAppend; /* More terms for ARRAY and OBJECT */
u32 iKey; /* Key for ARRAY objects in json_tree() */
u32 iReplace; /* Replacement content for JNODE_REPLACE */
JsonNode *pPatch; /* Node chain of patch for JNODE_PATCH */
} u;
};
@ -410,6 +412,13 @@ static void jsonRenderNode(
JsonString *pOut, /* Write JSON here */
sqlite3_value **aReplace /* Replacement values */
){
if( pNode->jnFlags & (JNODE_REPLACE|JNODE_PATCH) ){
if( pNode->jnFlags & JNODE_REPLACE ){
jsonAppendValue(pOut, aReplace[pNode->u.iReplace]);
return;
}
pNode = pNode->u.pPatch;
}
switch( pNode->eType ){
default: {
assert( pNode->eType==JSON_NULL );
@ -441,12 +450,7 @@ static void jsonRenderNode(
jsonAppendChar(pOut, '[');
for(;;){
while( j<=pNode->n ){
if( pNode[j].jnFlags & (JNODE_REMOVE|JNODE_REPLACE) ){
if( pNode[j].jnFlags & JNODE_REPLACE ){
jsonAppendSeparator(pOut);
jsonAppendValue(pOut, aReplace[pNode[j].iVal]);
}
}else{
if( (pNode[j].jnFlags & JNODE_REMOVE)==0 ){
jsonAppendSeparator(pOut);
jsonRenderNode(&pNode[j], pOut, aReplace);
}
@ -468,11 +472,7 @@ static void jsonRenderNode(
jsonAppendSeparator(pOut);
jsonRenderNode(&pNode[j], pOut, aReplace);
jsonAppendChar(pOut, ':');
if( pNode[j+1].jnFlags & JNODE_REPLACE ){
jsonAppendValue(pOut, aReplace[pNode[j+1].iVal]);
}else{
jsonRenderNode(&pNode[j+1], pOut, aReplace);
}
jsonRenderNode(&pNode[j+1], pOut, aReplace);
}
j += 1 + jsonNodeSize(&pNode[j+1]);
}
@ -699,7 +699,6 @@ static int jsonParseAddNode(
p = &pParse->aNode[pParse->nNode];
p->eType = (u8)eType;
p->jnFlags = 0;
p->iVal = 0;
p->n = n;
p->u.zJContent = zContent;
return pParse->nNode++;
@ -1357,6 +1356,104 @@ static void jsonExtractFunc(
jsonParseReset(&x);
}
/* This is the RFC 7396 MergePatch algorithm.
*/
static JsonNode *jsonMergePatch(
JsonParse *pParse, /* The JSON parser that contains the TARGET */
int iTarget, /* Node of the TARGET in pParse */
JsonNode *pPatch /* The PATCH */
){
int i, j;
int iApnd;
JsonNode *pTarget;
if( pPatch->eType!=JSON_OBJECT ){
return pPatch;
}
assert( iTarget>=0 && iTarget<pParse->nNode );
pTarget = &pParse->aNode[iTarget];
assert( (pPatch->jnFlags & JNODE_APPEND)==0 );
if( pTarget->eType!=JSON_OBJECT ){
for(i=2; i<pPatch->n; i += jsonNodeSize(&pPatch[i])+1){
if( pPatch[i].eType==JSON_NULL ){
pPatch[i-1].jnFlags |= JNODE_REMOVE;
}
}
return pPatch;
}
iApnd = iTarget;
for(i=1; i<pPatch->n; i += jsonNodeSize(&pPatch[i+1])+1){
int nKey;
const char *zKey;
assert( pPatch[i].eType==JSON_STRING );
assert( pPatch[i].jnFlags & JNODE_LABEL );
nKey = pPatch[i].n;
zKey = pPatch[i].u.zJContent;
if( (pPatch[i].jnFlags & JNODE_RAW)==0 ){
assert( nKey>=2 && zKey[0]=='"' && zKey[nKey-1]=='"' );
nKey -= 2;
zKey ++;
}
for(j=1; j<pTarget->n; j += jsonNodeSize(&pTarget[j+1])+1 ){
assert( pTarget[j].eType==JSON_STRING );
assert( pTarget[j].jnFlags & JNODE_LABEL );
if( jsonLabelCompare(&pTarget[j], zKey, nKey)
&& (pTarget[j+1].jnFlags & (JNODE_REMOVE|JNODE_PATCH))==0
){
if( pPatch[i+1].eType==JSON_NULL ){
pTarget[j+1].jnFlags |= JNODE_REMOVE;
}else{
JsonNode *pNew = jsonMergePatch(pParse, j+1, &pPatch[i+1]);
if( pNew==0 ) return 0;
pTarget = &pParse->aNode[iTarget];
if( pNew!=&pTarget[j+1] ){
pTarget[j+1].u.pPatch = pNew;
pTarget[j+1].jnFlags |= JNODE_PATCH;
}
}
break;
}
}
if( j>=pTarget->n ){
int iStart, iPatch;
iStart = jsonParseAddNode(pParse, JSON_OBJECT, 2, 0);
jsonParseAddNode(pParse, JSON_STRING, nKey, zKey);
iPatch = jsonParseAddNode(pParse, JSON_TRUE, 0, 0);
if( pParse->oom ) return 0;
pTarget = &pParse->aNode[iTarget];
pParse->aNode[iApnd].jnFlags |= JNODE_APPEND;
pParse->aNode[iApnd].u.iAppend = iStart;
iApnd = iStart;
pParse->aNode[iPatch].jnFlags |= JNODE_PATCH;
pParse->aNode[iPatch].u.pPatch = &pPatch[i+1];
}
}
return pTarget;
}
/*
** Implementation of the json_mergepatch(JSON1,JSON2) function. Return a JSON
** object that is the result of running the RFC 7396 MergePatch() algorithm
** on the two arguments.
*/
static void jsonMergePatchFunc(
sqlite3_context *ctx,
int argc,
sqlite3_value **argv
){
JsonParse x; /* The JSON that is being patched */
JsonParse y; /* The patch */
if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
if( jsonParse(&y, ctx, (const char*)sqlite3_value_text(argv[1])) ){
jsonParseReset(&x);
return;
}
jsonReturnJson(jsonMergePatch(&x, 0, y.aNode), ctx, 0);
jsonParseReset(&x);
jsonParseReset(&y);
}
/*
** Implementation of the json_object(NAME,VALUE,...) function. Return a JSON
** object that contains all name/value given in arguments. Or if any name
@ -1460,11 +1557,11 @@ static void jsonReplaceFunc(
if( x.nErr ) goto replace_err;
if( pNode ){
pNode->jnFlags |= (u8)JNODE_REPLACE;
pNode->iVal = (u8)(i+1);
pNode->u.iReplace = i + 1;
}
}
if( x.aNode[0].jnFlags & JNODE_REPLACE ){
sqlite3_result_value(ctx, argv[x.aNode[0].iVal]);
sqlite3_result_value(ctx, argv[x.aNode[0].u.iReplace]);
}else{
jsonReturnJson(x.aNode, ctx, argv);
}
@ -1514,11 +1611,11 @@ static void jsonSetFunc(
goto jsonSetDone;
}else if( pNode && (bApnd || bIsSet) ){
pNode->jnFlags |= (u8)JNODE_REPLACE;
pNode->iVal = (u8)(i+1);
pNode->u.iReplace = i + 1;
}
}
if( x.aNode[0].jnFlags & JNODE_REPLACE ){
sqlite3_result_value(ctx, argv[x.aNode[0].iVal]);
sqlite3_result_value(ctx, argv[x.aNode[0].u.iReplace]);
}else{
jsonReturnJson(x.aNode, ctx, argv);
}
@ -2160,6 +2257,7 @@ int sqlite3Json1Init(sqlite3 *db){
{ "json_array_length", 2, 0, jsonArrayLengthFunc },
{ "json_extract", -1, 0, jsonExtractFunc },
{ "json_insert", -1, 0, jsonSetFunc },
{ "json_mergepatch", 2, 0, jsonMergePatchFunc },
{ "json_object", -1, 0, jsonObjectFunc },
{ "json_quote", 1, 0, jsonQuoteFunc },
{ "json_remove", -1, 0, jsonRemoveFunc },