Add the decimal_sci(X) function to the Decimal extension for showing a decimal

value in scientific notation:  +D.DDDDDe+DD

FossilOrigin-Name: 61d4923913e88b980ce93db4f3f9f9d7ba3baaac724995c36c9b887c034accdc

ext/misc/decimal.c

@@ -230,6 +230,67 @@ static void decimal_result(sqlite3_context *pCtx, Decimal *p){
   sqlite3_result_text(pCtx, z, i, sqlite3_free);
 }
 
+/*
+** Make the given Decimal the result in an format similar to  '%+#e'.
+** In other words, show exponential notation with leading and trailing
+** zeros omitted.
+*/
+static void decimal_result_sci(sqlite3_context *pCtx, Decimal *p){
+  char *z;       /* The output buffer */
+  int i;         /* Loop counter */
+  int nZero;     /* Number of leading zeros */
+  int nDigit;    /* Number of digits not counting trailing zeros */
+  int nFrac;     /* Digits to the right of the decimal point */
+  int exp;       /* Exponent value */
+  signed char zero;     /* Zero value */
+  signed char *a;       /* Array of digits */
+
+  if( p==0 || p->oom ){
+    sqlite3_result_error_nomem(pCtx);
+    return;
+  }
+  if( p->isNull ){
+    sqlite3_result_null(pCtx);
+    return;
+  }
+  for(nDigit=p->nDigit; nDigit>0 && p->a[nDigit-1]==0; nDigit--){}
+  for(nZero=0; nZero<nDigit && p->a[nZero]==0; nZero++){}
+  nFrac = p->nFrac + (nDigit - p->nDigit);
+  nDigit -= nZero;
+  z = sqlite3_malloc( nDigit+20 );
+  if( z==0 ){
+    sqlite3_result_error_nomem(pCtx);
+    return;
+  }
+  if( nDigit==0 ){
+    zero = 0;
+    a = &zero;
+    nDigit = 1;
+    nFrac = 0;
+  }else{
+    a = &p->a[nZero];
+  }
+  if( p->sign && nDigit>0 ){
+    z[0] = '-';
+  }else{
+    z[0] = '+';
+  }
+  z[1] = a[0]+'0';
+  z[2] = '.';
+  if( nDigit==1 ){
+    z[3] = '0';
+    i = 4;
+  }else{
+    for(i=1; i<nDigit; i++){
+      z[2+i] = a[i]+'0';
+    }
+    i = nDigit+2;
+  }
+  exp = nDigit - nFrac - 1;
+  sqlite3_snprintf(nDigit+20-i, &z[i], "e%+03d", exp);
+  sqlite3_result_text(pCtx, z, -1, sqlite3_free);
+}
+
 /*
 ** SQL Function:   decimal(X)
 **
@@ -591,6 +652,21 @@ mul_end:
   decimal_free(pB);
 }
 
+/*
+** SQL Function:   decimal_sci(X)
+**
+** Convert decimal number X into scientific notation ("+N.NNNe+NN").
+*/
+static void decimalSciFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  Decimal *pA = decimal_new(context, argv[0], 0, 0);
+  decimal_result_sci(context, pA);
+  decimal_free(pA);
+}
+
 #ifdef _WIN32
 __declspec(dllexport)
 #endif
@@ -610,6 +686,7 @@ int sqlite3_decimal_init(
     { "decimal_add",   2,   decimalAddFunc     },
     { "decimal_sub",   2,   decimalSubFunc     },
     { "decimal_mul",   2,   decimalMulFunc     },
+    { "decimal_sci",   1,   decimalSciFunc     },
   };
   unsigned int i;
   (void)pzErrMsg;  /* Unused parameter */

manifest

@@ -1,5 +1,5 @@
-C CLI\senhancements\sto\sfacilitate\sSQLite\score\stesting:\n(1)\sAdd\sbuilt-in\sfunctions\sstrtod()\sand\sdtostr()\sthat\sconvert\stext\sto\nfloating\spoint\sand\sback\susing\sC-library\sroutines.\n(2)\sDo\snot\sdisable\sall\sof\s".testctrl"\swithout\s--unsafe-testing,\sbut\sonly\nthose\ssubcommands\sof\s.testctrl\sthat\sare\sactually\sdangerous.
-D 2023-06-29T12:14:10.203
+C Add\sthe\sdecimal_sci(X)\sfunction\sto\sthe\sDecimal\sextension\sfor\sshowing\sa\sdecimal\nvalue\sin\sscientific\snotation:\s\s+D.DDDDDe+DD
+D 2023-06-29T14:49:23.326
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -287,7 +287,7 @@ F ext/misc/completion.c 6dafd7f4348eecc7be9e920d4b419d1fb2af75d938cd9c59a20cfe8b
 F ext/misc/compress.c 3354c77a7c8e86e07d849916000cdac451ed96500bfb5bd83b20eb61eee012c9
 F ext/misc/csv.c ca8d6dafc5469639de81937cb66ae2e6b358542aba94c4f791910d355a8e7f73
 F ext/misc/dbdump.c b8592f6f2da292c62991a13864a60d6c573c47a9cc58362131b9e6a64f823e01
-F ext/misc/decimal.c 57d85fa20a5a74d3b0dfc78ab7934ae6c9f5aa8eed915faa2b5246bec87ddc6d
+F ext/misc/decimal.c 17303ac06f50d750fdb635c8be1f8eb820fa95896fd08c08af332b62fe8bcfce
 F ext/misc/eval.c 04bc9aada78c888394204b4ed996ab834b99726fb59603b0ee3ed6e049755dc1
 F ext/misc/explain.c 0086fab288d4352ea638cf40ac382aad3b0dc5e845a1ea829a694c015fd970fe
 F ext/misc/fileio.c 4e7f7cd30de8df4820c552f14af3c9ca451c5ffe1f2e7bef34d598a12ebfb720
@@ -2041,8 +2041,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
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-P a915f15a916af698e0cef46c8b3e7ed11bda19349179d2d414073cd39c4cce24
-R 0ff1aaf83c3a4b2103ba6e2bba60a2a8
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+R 090cbc96cc5b169f2dbe66c47db5bae8
 U drh
-Z f9cb0e945d7f18774016bacc44534d0c
+Z d52f599d2e14938fb14fb03c95733f3a
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-669996a8ddcbf35f3de66cf466508fc1e6dd09ab269aba395ac86a11b2ec238c
+61d4923913e88b980ce93db4f3f9f9d7ba3baaac724995c36c9b887c034accdc