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#1054. Replaced the reference mess with a beautiful one-line recursion. Interation is interesting; recursion is really elegant.

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Robin Mills 2015-04-10 18:42:09 +00:00
parent ffba84261f
commit 4f6b747478
1 changed files with 14 additions and 29 deletions
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43
samples/exiv2json.cpp
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@ -92,6 +92,11 @@ Jzon::Node& addToTree(Jzon::Node& r1,Token token)
return r1;
}
Jzon::Node& addToTree(Jzon::Node& rt,Tokens& tokens,size_t k)
{
return --k == 0 ? addToTree(rt,tokens[0]) : addToTree( addToTree(rt,tokens,k) ,tokens[k]);
}
// build the json tree for this key. return location and discover the name
Jzon::Node& objectForKey(const std::string Key,Jzon::Object& rt,std::string& name)
{
@ -104,37 +109,17 @@ Jzon::Node& objectForKey(const std::string Key,Jzon::Object& rt,std::string& nam
name = token.n ;
}
size_t l = tokens.size()-1; // leave leaf name to push()
return addToTree(rt,tokens,l);
// this is horrible
// why can't you have an array of references?
// why can't you change a reference without disturbing the referenced object?
// why can't you new() a reference?
// references are pointers that don't work properly!
#if 1
size_t k = 0;
Jzon::Node& r1 = addToTree( rt,tokens[k++]) ; if ( l == k ) return r1;
Jzon::Node& r2 = addToTree( r1,tokens[k++]) ; if ( l == k ) return r2;
Jzon::Node& r3 = addToTree( r2,tokens[k++]) ; if ( l == k ) return r3;
Jzon::Node& r4 = addToTree( r3,tokens[k++]) ; if ( l == k ) return r4;
Jzon::Node& r5 = addToTree( r4,tokens[k++]) ; if ( l == k ) return r5;
Jzon::Node& r6 = addToTree( r5,tokens[k++]) ; if ( l == k ) return r6;
Jzon::Node& r7 = addToTree( r6,tokens[k++]) ; if ( l == k ) return r7;
Jzon::Node& r8 = addToTree( r7,tokens[k++]) ; if ( l == k ) return r8;
Jzon::Node& r9 = addToTree( r8,tokens[k++]) ; if ( l == k ) return r9;
Jzon::Node& r10 = addToTree( r9,tokens[k++]) ; if ( l == k ) return r10;
Jzon::Node& r11 = addToTree(r10,tokens[k++]) ; if ( l == k ) return r11;
#else
// We could express this prettily as:
// Still horrible. There has to be a way to express this to any depth
if ( l == 1 ) return addToTree(rt,tokens[0]);
if ( l == 2 ) return addToTree(addToTree(rt,tokens[0]),tokens[1]);
if ( l == 3 ) return addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]);
if ( l == 4 ) return addToTree(addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]),tokens[3]);
if ( l == 5 ) return addToTree(addToTree(addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]),tokens[3]),tokens[4]);
if ( l == 6 ) return addToTree(addToTree(addToTree(addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]),tokens[3]),tokens[4]),tokens[5]);
if ( l == 7 ) return addToTree(addToTree(addToTree(addToTree(addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]),tokens[3]),tokens[4]),tokens[5]),tokens[6]);
#if 0
// The recursion could be expressed these if statements:
// Go to the root, and climb out, adding objects or arrays to create the tree
// The leaf is pushed onto the top by the caller of objectForKey!
if ( l == 1 ) return addToTree(rt,tokens[0]);
if ( l == 2 ) return addToTree(addToTree(rt,tokens[0]),tokens[1]);
if ( l == 3 ) return addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]);
if ( l == 4 ) return addToTree(addToTree(addToTree(addToTree(rt,tokens[0]),tokens[1]),tokens[2]),tokens[3]);
#endif
return rt ;
}
bool isObject(std::string& value)