parseRow() efficiency + related realloc fix

Author: michalmonday

CSV_Parser.cpp

@@ -86,6 +86,9 @@ CSV_Parser::CSV_Parser(const char * s, const char * fmt_, bool has_header_, char
   keys =   (char**)calloc(cols_count, sizeof(char*));         // calloc fills memory with 0's so then I can simply use "if(keys[i]) { do something with key[i] }"
   values = (void**)calloc(cols_count, sizeof(void*));
 
+  for (int col = 0; col < cols_count; col++)
+      values[col] = malloc(getTypeSize(fmt[col])); 
+
   /*mem.check("constructor");
   mem.check("after calloc 1, should be = " + String(cols_count * sizeof(char*)));
   mem.check("after calloc 2, should be = " + String(cols_count * sizeof(void*)));*/ 
@@ -123,9 +126,11 @@ bool CSV_Parser::parseRow() {
   // (by "original way of parsing" I mean: by using "cp <<" operator or by supplying whole csv at once)
   // parseRow() requires feedRowParser() and rowParserFinished() to be defined by the user
   // It then allows to read the first row in the same way as default parsing way, like:
-  // while (cp.parseRow()) { 
-  //    char *str = ((char**)cp["my_strings"])[0];
-  // }
+  //
+  //     char **strings = (char**)cp[0]; // string based indexing can't be used here because header was not supplied yet
+  //     while (cp.parseRow()) { 
+  //        char *str = strings[0];
+  //     }
 
   if (rowParserFinished()) 
     return false;
@@ -441,7 +446,8 @@ void CSV_Parser::supplyChunk(const char *s) {
         keys[current_col] = strdup_trimmed(val);
       } else {
         //mem.check("values[" + String(current_col) + "]");
-        values[current_col] = (char*)realloc(values[current_col], (rows_count+1) * getTypeSize(fmt[current_col])); 
+        if (rows_count > 0)
+          values[current_col] = (char*)realloc(values[current_col], (rows_count+1) * getTypeSize(fmt[current_col])); 
         saveNewValue(val, fmt[current_col], rows_count, current_col, is_fmt_unsigned[current_col]);
       }
     }
@@ -500,7 +506,8 @@ void CSV_Parser::parseLeftover() {
     int chars_occupied = 0;
     if (char * val = parseStringValue(leftover, &chars_occupied)) {
       if (fmt[current_col] != '-') {
-        values[current_col] = realloc(values[current_col], (rows_count+1) * getTypeSize(fmt[current_col]));
+        if (rows_count > 0)
+          values[current_col] = realloc(values[current_col], (rows_count+1) * getTypeSize(fmt[current_col]));
         saveNewValue(val, fmt[current_col], rows_count, current_col, is_fmt_unsigned[current_col]);  
       }
       if (++current_col == cols_count) {

examples/parsing_row_by_row/parsing_row_by_row.ino

@@ -77,16 +77,24 @@ void setup() {
   CSV_Parser cp(/*format*/ "sL");
 
   Serial.println("Accessing values by column name:");
+  
+  // WARNING: String indexing can't be used here because the header was not supplied to the cp object yet.
+  // char **strings = (char**)cp["my_strings"];
+  // int32_t *numbers = (int32_t*)cp["my_numbers"];
+
+  char **strings = (char**)cp[0];
+  int32_t *numbers = (int32_t*)cp[1];
 
   // parseRow calls feedRowParser() continuously until it reads a 
   // full row or until the rowParserFinished() returns true
   int row_index = 0;
   while (cp.parseRow()) {
-    char *string = ((char**)cp["my_strings"])[0];
-    int32_t number = ((int32_t*)cp["my_numbers"])[0];
+    // Here we could use string indexing but it would be much slower.
+    // char *string = ((char**)cp["my_strings"])[0];
+    // int32_t number = ((int32_t*)cp["my_numbers"])[0];
 
-//    char *string = ((char**)cp[0])[0];
-//    int32_t number = ((int32_t*)cp[1])[0];
+    char *string = strings[0];
+    int32_t number = numbers[0];
 
     Serial.print(String(row_index) + ". String = ");
     Serial.println(string);