# HG changeset patch
# User jbe
# Date 1452788028 -3600
# Node ID f0303fca9218d21cd6cb4ca0883ba505bcf53ef8
# Parent  9d15451c340a5acde19fb82521711c4a0b221a87
Decode some JSON numbers (those without decimal point or exponential notation) as Lua integers

diff -r 9d15451c340a -r f0303fca9218 libraries/json/json.c
--- a/libraries/json/json.c	Thu Jan 14 12:49:54 2016 +0100
+++ b/libraries/json/json.c	Thu Jan 14 17:13:48 2016 +0100
@@ -544,17 +544,44 @@
   }
   // process values whose type is is not deducible from a single character:
   if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
-    // for numbers,
-    // use strtod() call to parse a (double precision) floating point number:
+    // try to parse number:
     double numval;
     char *endptr;
+    size_t endpos;
+    // use strtod() call to parse a (double precision) floating point number
+    // and to determine length of number:
     numval = strtod(str+pos, &endptr);
     // catch parsing errors:
     if (endptr == str+pos) goto json_import_syntax_error;
+    // calculate end position of number:
+    endpos = endptr - str;
+#if LUA_VERSION_NUM >= 503
+    // try alternative integer interpretation:
+    {
+      lua_Integer intval = 0;
+      size_t curpos;
+      if (c >= '0' && c <= '9') intval = c - '0';
+      for (curpos=pos+1; curpos<endpos; curpos++) {
+        lua_Integer d = str[curpos] - '0';
+        if (d < 0 || d > 9) break;
+        if (c == '-') {
+          // NOTE: rounding of negative integer division may be undefined
+          if (
+            intval == LUA_MININTEGER ||
+            -intval > (-(LUA_MININTEGER+10) - d) / 10 + 1
+          ) break;
+          intval = 10 * intval - d;
+        } else {
+          if (intval > (LUA_MAXINTEGER - d) / 10) break;
+          intval = 10 * intval + d;
+        }
+      }
+      if (curpos == endpos) lua_pushinteger(L, intval);
+      else lua_pushnumber(L, numval);
+    }
+#endif
     // consume characters that were parsed:
-    pos += endptr - (str+pos);
-    // push parsed (double precision) floating point number on Lua stack:
-    lua_pushnumber(L, numval);
+    pos = endpos;
   } else if (!strncmp(str+pos, "true", 4)) {
     // consume 4 input characters for "true":
     pos += 4;
@@ -597,11 +624,11 @@
   case JSON_STATE_ARRAY_VALUE:
     // get current array length:
     arraylen = lua_rawlen(L, -3);
-    // throw error if array would exceed INT_MAX elements:
-    // TODO: Lua 5.3 may support more elements
-    if (arraylen >= INT_MAX) {
+    // throw error if array would exceed INT_MAX-1 elements:
+    // NOTE: Lua 5.3 may support more elements, but C libraries may not
+    if (arraylen > INT_MAX-1) {
       lua_pushnil(L);
-      lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX);
+      lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX-1);
     }
     // store value in outer shadow table:
     lua_rawseti(L, -3, arraylen + 1);