Input consuming.

It's possible that this commit contains errors, since I'm writing this
on a Windows machine and the compiler seems bad. I'll compile this in a
Linux machine and fix any errors present in the following commit.

data/test_mat.txt

@@ -0,0 +1,4 @@
+3
+1    1    -1
+555  0.9  +2
+-55  2    1555

make.py

@@ -7,8 +7,9 @@ from sane import *
 
 COMPILER = 'gcc'
 COMPILE_FLAGS = ['-g',
-                 '-Wall',
                  '--std=c99',
+                 '-Wall',
+                 '-Werror',
                  '-fopenmp']
 LINK_FLAGS = []
 OBJ_DIR = 'obj'

src/main.c

@@ -1,11 +1,177 @@
+#include <stdlib.h>
 #include <stdio.h>
 #include <stddef.h>
 #include <inttypes.h>
+#include <ctype.h>
 
-#define STB_DS_IMPLEMENTATION
-#include "../contrib/stb/stb_ds.h"
+// #define STB_DS_IMPLEMENTATION
+// #define STBDS_NO_SHORT_NAMES
+// #include "../contrib/stb/stb_ds.h"
 
-int main(int argc, char *argv[]) {
+#define PRIgridDATA PRIiFAST32
+typedef int_fast32_t grid_data_t;
 
+typedef struct
+{
+  // Number of elements in one row.
+  size_t row_len;
+  // Pointer to the buffer containing the matrix's characters.
+  // The data is organized as <string length> <chars...>, such that the `char`s
+  // are casted to `int_fast32_t` to allow for the mixed types.
+  grid_data_t *data_head;
+  // Array of pointers to the start of each entry string.
+  grid_data_t **entries_head;
+  // Number of elements.
+  size_t data_len;
+} grid_t;
+
+// Parameters for `increase_input_buffers`.
+typedef struct
+{
+  size_t data_cap;
+  grid_data_t *data_head;
+  grid_data_t **entries_head;
+} increase_input_buffers_params_t;
+
+// Prints a debug view of a `grid_t` to standard output.
+void debug_print_grid(grid_t *grid)
+{
+  printf("Grid { row_len: %zu, data_head: %p, entries_head: %p, data_len: %zu }",
+         (grid->row_len), (void*)(grid->data_head), (void*)(grid->entries_head),
+         (grid->data_len));
+}
+
+// Increases the data buffers used in `parse_input`.
+//
+// As reallocation will happen, the updated pointers and capacity are returned
+// in an updated parameters object.
+increase_input_buffers_params_t increase_input_buffers(increase_input_buffers_params_t params)
+{
+  params.data_cap *= 2;
+  params.data_head = realloc(params.data_head, params.data_cap * sizeof(grid_data_t));
+  params.entries_head = realloc(params.entries_head, params.data_cap * sizeof(grid_data_t *));
+  if ((params.data_head == NULL) || (params.entries_head == NULL))
+  {
+    printf(
+        "Failed to reallocate bigger buffer for input data. Was trying to "
+        "allocate %zu entries, aborting.",
+        params.data_cap);
+    exit(EXIT_FAILURE);
+  }
+  return params;
+}
+
+// Parse the input from standard input.
+//
+// This function parses an extended matrix (C|l), where C is an n×m matrix, and
+// l is an m-sized column vector. This input is given in standard input as
+//
+//  <row length> <whitespace separated entries>
+//
+// Parsing the entries of the matrix as numeric is unnecessary, since we just
+// want to check equality of rows under certain permutations. Therefore, the
+// matrix is stored as literal characters.
+//
+// To make data access O(1), we store both the literal characters, as well as
+// indices to the start of each entry. See the `Grid` struct. In particular,
+// what we have is contiguous blocks of strings, structured as
+//
+//  <string length> <characters...>
+grid_t parse_input(void)
+{
+  size_t row_len;
+  scanf("%zu", &row_len);
+
+  size_t data_cap = 32; // Initial value is arbitrary.
+  size_t data_len = 0;  // Number of characters written so far.
+  size_t str_len = 0;   // Number of strings written so far.
+  grid_data_t *data_head = malloc(data_cap * sizeof(grid_data_t));
+  size_t *entries_head = malloc(data_cap * sizeof(size_t));
+
+  _Bool spaces = 1;
+  char scanned;
+  while ((scanned = scanf("%c", &scanned)) != EOF)
+  {
+    if (isspace(scanned))
+    {
+      spaces = 1;
+    }
+    else
+    {
+      // A little input sanitization.
+      if (scanned == '+')
+      {
+        // We can ignore plus signs, assuming we have (\+|\-)?\d+(\.\d+)?(E\d+)?
+        continue;
+      }
+      if (!(isdigit(scanned) || (scanned == '-') || (scanned == '.')))
+      {
+        printf(
+            "Foreign character %c found when processing input, aborting.",
+            scanned);
+        exit(EXIT_FAILURE);
+      }
+
+      if (spaces)
+      {
+        // New row
+        str_len += 1;
+        data_len += 1; // The byte for the string length
+        // data_head[data_len] is already correctly initialized to 0.
+        entries_head[str_len - 1] = data_len - 1;
+      }
+      spaces = 0;
+
+      // We're about to write a new character.
+      data_len += 1;
+
+      // Check if we need to resize the buffer.
+      if (data_len > data_cap)
+      {
+        increase_input_buffers_params_t params = {
+            .data_cap = data_cap,
+            .data_head = data_head,
+            .entries_head = entries_head,
+        };
+        params = increase_input_buffers(params);
+        data_cap = params.data_cap;
+        data_head = params.data_head;
+        entries_head = params.entries_head;
+      }
+
+      // Write the character
+      data_head[data_len - 1] = scanned;
+
+      // Increase the length of current string
+      grid_data_t *cur_len = entries_head[str_len - 1];
+      *cur_len += 1;
+    }
+  } // End of scan loop
+
+  // Input sanitization: confirm that the number of entries read is a multiple
+  // of the number of entries in a row.
+  if (!((str_len % row_len) == 0))
+  {
+    printf("Number of entries is not consistent with provided row length. "
+           "Got row length of %zu, and read %zu entries. Aborting.",
+           row_len, str_len);
+    // No need to free the buffers.
+    exit(EXIT_FAILURE);
+  }
+
+  grid_t grid = {
+      .row_len = row_len,
+      .data_head = data_head,
+      .entries_head = entries_head,
+      .data_len = data_len,
+  };
+
+  return grid;
+}
+
+int main(int argc, char *argv[])
+{
+  grid_t grid = parse_input();
+  debug_print_grid(&grid);
   return 0;
 }