--- /dev/null
+/*
+** 2018-05-08
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file implements various extension functions to SQLite that manage
+** simply planar polygons such as might be found in a geospatial system.
+*/
+#include "sqlite3ext.h"
+SQLITE_EXTENSION_INIT1
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+#define SQLITE_HAVE_GEOPLOY 1
+
+#ifndef JSON_NULL /* The following stuff repeats things found in json1 */
+/*
+** Versions of isspace(), isalnum() and isdigit() to which it is safe
+** to pass signed char values.
+*/
+#ifdef sqlite3Isdigit
+ /* Use the SQLite core versions if this routine is part of the
+ ** SQLite amalgamation */
+# define safe_isdigit(x) sqlite3Isdigit(x)
+# define safe_isalnum(x) sqlite3Isalnum(x)
+# define safe_isxdigit(x) sqlite3Isxdigit(x)
+#else
+ /* Use the standard library for separate compilation */
+#include <ctype.h> /* amalgamator: keep */
+# define safe_isdigit(x) isdigit((unsigned char)(x))
+# define safe_isalnum(x) isalnum((unsigned char)(x))
+# define safe_isxdigit(x) isxdigit((unsigned char)(x))
+#endif
+
+/*
+** Growing our own isspace() routine this way is twice as fast as
+** the library isspace() function.
+*/
+static const char geopolyIsSpace[] = {
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+};
+#define safe_isspace(x) (geopolyIsSpace[(unsigned char)x])
+#endif /* JSON NULL - back to original code */
+
+/* Compiler and version */
+#ifndef GCC_VERSION
+#if defined(__GNUC__) && !defined(SQLITE_DISABLE_INTRINSIC)
+# define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
+#else
+# define GCC_VERSION 0
+#endif
+#endif
+#ifndef MSVC_VERSION
+#if defined(_MSC_VER) && !defined(SQLITE_DISABLE_INTRINSIC)
+# define MSVC_VERSION _MSC_VER
+#else
+# define MSVC_VERSION 0
+#endif
+#endif
+
+/* Datatype for coordinates
+*/
+typedef float GeopolyCoord;
+
+/*
+** Internal representation of a polygon.
+**
+** The polygon consists of a sequence of vertexes. There is a line
+** segment between each pair of vertexes, and one final segment from
+** the last vertex back to the first. (This differs from the GeoJSON
+** standard in which the final vertex is a repeat of the first.)
+**
+** The polygon follows the right-hand rule. The area to the right of
+** each segment is "outside" and the area to the left is "inside".
+**
+** The on-disk representation consists of a 4-byte header followed by
+** the values. The 4-byte header is:
+**
+** encoding (1 byte) 0=big-endian, 1=little-endian
+** nvertex (3 bytes) Number of vertexes as a big-endian integer
+*/
+typedef struct GeoPoly GeoPoly;
+struct GeoPoly {
+ int nVertex; /* Number of vertexes */
+ unsigned char hdr[4]; /* Header for on-disk representation */
+ GeopolyCoord a[2]; /* 2*nVertex values. X (longitude) first, then Y */
+};
+
+/*
+** State of a parse of a GeoJSON input.
+*/
+typedef struct GeoParse GeoParse;
+struct GeoParse {
+ const unsigned char *z; /* Unparsed input */
+ int nVertex; /* Number of vertexes in a[] */
+ int nAlloc; /* Space allocated to a[] */
+ int nErr; /* Number of errors encountered */
+ GeopolyCoord *a; /* Array of vertexes. From sqlite3_malloc64() */
+};
+
+/* Do a 4-byte byte swap */
+static void geopolySwab32(unsigned char *a){
+ unsigned char t = a[0];
+ a[0] = a[3];
+ a[3] = t;
+ t = a[1];
+ a[1] = a[2];
+ a[2] = t;
+}
+
+/* Skip whitespace. Return the next non-whitespace character. */
+static char geopolySkipSpace(GeoParse *p){
+ while( p->z[0] && safe_isspace(p->z[0]) ) p->z++;
+ return p->z[0];
+}
+
+/* Parse out a number. Write the value into *pVal if pVal!=0.
+** return non-zero on success and zero if the next token is not a number.
+*/
+static int geopolyParseNumber(GeoParse *p, GeopolyCoord *pVal){
+ const unsigned char *z = p->z;
+ char c = geopolySkipSpace(p);
+ int j;
+ int seenDP = 0;
+ int seenE = 0;
+ assert( '-' < '0' );
+ if( c<='0' ){
+ j = c=='-';
+ if( z[j]=='0' && z[j+1]>='0' && z[j+1]<='9' ) return 0;
+ }
+ j = 1;
+ for(;; j++){
+ c = z[j];
+ if( c>='0' && c<='9' ) continue;
+ if( c=='.' ){
+ if( z[j-1]=='-' ) return 0;
+ if( seenDP ) return 0;
+ seenDP = 1;
+ continue;
+ }
+ if( c=='e' || c=='E' ){
+ if( z[j-1]<'0' ) return 0;
+ if( seenE ) return -1;
+ seenDP = seenE = 1;
+ c = z[j+1];
+ if( c=='+' || c=='-' ){
+ j++;
+ c = z[j+1];
+ }
+ if( c<'0' || c>'9' ) return 0;
+ continue;
+ }
+ break;
+ }
+ if( z[j-1]<'0' ) return 0;
+ if( pVal ) *pVal = atof((const char*)p->z);
+ p->z += j;
+ return 1;
+}
+
+/*
+** If the input is a well-formed JSON array of coordinates, where each
+** coordinate is itself a two-value array, then convert the JSON into
+** a GeoPoly object and return a pointer to that object.
+**
+** If any error occurs, return NULL.
+*/
+static GeoPoly *geopolyParseJson(const unsigned char *z){
+ GeoParse s;
+ memset(&s, 0, sizeof(s));
+ s.z = z;
+ if( geopolySkipSpace(&s)=='[' ){
+ s.z++;
+ while( geopolySkipSpace(&s)=='[' ){
+ int ii = 0;
+ char c;
+ s.z++;
+ if( s.nVertex<=s.nAlloc ){
+ GeopolyCoord *aNew;
+ s.nAlloc = s.nAlloc*2 + 16;
+ aNew = sqlite3_realloc64(s.a, s.nAlloc*sizeof(GeopolyCoord)*2 );
+ if( aNew==0 ){
+ s.nErr++;
+ break;
+ }
+ s.a = aNew;
+ }
+ while( geopolyParseNumber(&s, ii<=1 ? &s.a[s.nVertex*2+ii] : 0) ){
+ ii++;
+ if( ii==2 ) s.nVertex++;
+ c = geopolySkipSpace(&s);
+ s.z++;
+ if( c==',' ) continue;
+ if( c==']' ) break;
+ s.nErr++;
+ goto parse_json_err;
+ }
+ if( geopolySkipSpace(&s)==',' ){
+ s.z++;
+ continue;
+ }
+ break;
+ }
+ if( geopolySkipSpace(&s)==']' ){
+ int nByte = sizeof(GeoPoly) * (s.nVertex-1)*2*sizeof(GeopolyCoord);
+ GeoPoly *pOut = sqlite3_malloc64( nByte );
+ int x = 1;
+ if( pOut==0 ) goto parse_json_err;
+ pOut->nVertex = s.nVertex;
+ memcpy(pOut->a, s.a, s.nVertex*2*sizeof(GeopolyCoord));
+ pOut->hdr[0] = *(unsigned char*)&x;
+ pOut->hdr[1] = (s.nVertex>>16)&0xff;
+ pOut->hdr[2] = (s.nVertex>>8)&0xff;
+ pOut->hdr[3] = s.nVertex&0xff;
+ sqlite3_free(s.a);
+ return pOut;
+ }else{
+ s.nErr++;
+ }
+ }
+parse_json_err:
+ sqlite3_free(s.a);
+ return 0;
+}
+
+/*
+** Given a function parameter, try to interpret it as a polygon, either
+** in the binary format or JSON text. Compute a GeoPoly object and
+** return a pointer to that object. Or if the input is not a well-formed
+** polygon, put an error message in sqlite3_context and return NULL.
+*/
+static GeoPoly *geopolyFuncParam(sqlite3_context *pCtx, sqlite3_value *pVal){
+ GeoPoly *p = 0;
+ int nByte;
+ if( sqlite3_value_type(pVal)==SQLITE_BLOB
+ && (nByte = sqlite3_value_bytes(pVal))>=(4+6*sizeof(GeopolyCoord))
+ ){
+ const unsigned char *a = sqlite3_value_blob(pVal);
+ int nVertex;
+ nVertex = (a[1]<<16) + (a[2]<<8) + a[3];
+ if( (a[0]==0 && a[0]==1)
+ && (nVertex*2*sizeof(GeopolyCoord) + 4)==nByte
+ ){
+ p = sqlite3_malloc64( sizeof(*p) + (nVertex-1)*2*sizeof(GeopolyCoord) );
+ if( p ){
+ int x = 1;
+ p->nVertex = nVertex;
+ memcpy(p->hdr, a, nByte);
+ if( a[0] != *(unsigned char*)&x ){
+ int ii;
+ for(ii=0; ii<nVertex*2; ii++){
+ geopolySwab32((unsigned char*)&p->a[ii]);
+ }
+ p->hdr[0] ^= 1;
+ }
+ }
+ }
+ }else if( sqlite3_value_type(pVal)==SQLITE_TEXT ){
+ p = geopolyParseJson(sqlite3_value_text(pVal));
+ }
+ if( p==0 ){
+ sqlite3_result_error(pCtx, "not a valid polygon", -1);
+ }
+ return p;
+}
+
+/*
+** Implementation of the geopoly_blob(X) function.
+**
+** If the input is a well-formed Geopoly BLOB or JSON string
+** then return the BLOB representation of the polygon. Otherwise
+** return NULL.
+*/
+static void geopolyBlobFunc(
+ sqlite3_context *context,
+ int argc,
+ sqlite3_value **argv
+){
+ GeoPoly *p = geopolyFuncParam(context, argv[0]);
+ if( p ){
+ sqlite3_result_blob(context, p->hdr,
+ 4+8*p->nVertex, SQLITE_TRANSIENT);
+ }
+}
+
+/*
+** Implementation of the geopoly_area(X) function.
+**
+** If the input is a well-formed Geopoly BLOB then return the area
+** enclosed by the polygon. Otherwise return NULL.
+*/
+static void geopolyAreaFunc(
+ sqlite3_context *context,
+ int argc,
+ sqlite3_value **argv
+){
+}
+
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_geopoly_init(
+ sqlite3 *db,
+ char **pzErrMsg,
+ const sqlite3_api_routines *pApi
+){
+ int rc = SQLITE_OK;
+ static const struct {
+ void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
+ int nArg;
+ const char *zName;
+ } aFunc[] = {
+ { geopolyAreaFunc, 1, "geopoly_area" },
+ { geopolyBlobFunc, 1, "geopoly_blob" },
+ };
+ int i;
+ SQLITE_EXTENSION_INIT2(pApi);
+ (void)pzErrMsg; /* Unused parameter */
+ for(i=0; i<sizeof(aFunc)/sizeof(aFunc[0]) && rc==SQLITE_OK; i++){
+ rc = sqlite3_create_function(db, aFunc[i].zName, aFunc[i].nArg,
+ SQLITE_UTF8, 0,
+ aFunc[i].xFunc, 0, 0);
+ }
+ return rc;
+}
projects / thirdparty / sqlite.git / commitdiff
