commit 435fab86e3cec53ff2ee5aef7615859f9fbf98bf
Author: hellerve <veit@veitheller.de>
Date:   Wed Mar 18 23:08:40 2020 +0100

    initial

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..a2cd742
--- /dev/null
+++ b/README.md
@@ -0,0 +1,48 @@
+# cfg
+
+is a spartan fast configuration language.
+
+It has numbers, strings, lists, and sections.
+
+The reference implementation is WIP. I just got to finishing the data type and
+pretty printer today, a parser will be provided soon. I didn’t quite create a
+correct implementation today. There will most certainly also be memory leaks.
+I promised a friend I would share this “later today”, though, and I’m not one
+to break promises just because my code is crap. You have been warned.
+
+You’re not alone: I also wish the code were documented.
+
+## Example
+
+`cfg` has no comments, but let’s pretend we had `#` comments.
+
+```
+# lists start with a name, then an indent, and then a value
+my_list
+  - "value"
+  - 12
+
+# strings are quoted
+my_string "this is a string"
+
+# all numbers are doubles
+my_num 42.0
+
+# sections have names, and are indented by 2
+my_section
+  my_inner_string "inner"
+  my_second_numer 23.0
+```
+
+Keys cannot contain spaces. This is all.
+
+It is a simple format, some might think it is too simple. It is, however,
+possible, to write a simple, fast implementation in a few hundred lines of C
+(QED), and that might be worth a bit of reduction.
+
+See the [`examples/](examples/) directory for an example of how to use the
+pretty printer.
+
+<hr/>
+
+Have fun!
diff --git a/cfg.h b/cfg.h
new file mode 100644
index 0000000..78c3b47
--- /dev/null
+++ b/cfg.h
@@ -0,0 +1,446 @@
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+
+// Utilities
+
+size_t max(size_t a, size_t b) { return a > b ? a : b; }
+
+// Data types: list, string and map
+
+//// Constants
+
+#define DEFAULT_LIST_SIZE 8
+#define GROWTH_FACTOR 2
+
+//// Data types
+
+///// string is a string with a length and a capacity
+
+typedef struct string {
+  size_t len;
+  size_t cap;
+  char* str;
+} string;
+
+//// Functions
+
+///// string functions
+
+string new_string() {
+  string s;
+  s.len = 0;
+  s.cap = 0;
+  s.str = NULL;
+  return s;
+}
+
+string new_string_sized(size_t size) {
+  string s;
+  s.len = 0;
+  s.cap = size;
+  s.str = calloc(size, sizeof(char));
+  return s;
+}
+
+void free_string(string s) {
+  free(s.str);
+}
+
+char* string_cstr(string* s) {
+  char* c = malloc(s->len+1);
+  memcpy(c, s->str, s->len);
+  c[s->len] = '\0';
+  return c;
+}
+
+string string_from_cstr(char* c) {
+  int l = strlen(c);
+  string s = new_string_sized(l);
+  s.len = l;
+  memcpy(s.str, c, s.len);
+  return s;
+}
+
+void string_grow_min(string* s, size_t min_growth) {
+  s->cap = max(min_growth, s->cap*GROWTH_FACTOR);
+  s->str = realloc(s->str, s->cap);
+}
+
+void string_cappend(string* s, char* c) {
+  size_t l = strlen(c);
+  if (s->cap < s->len + l) string_grow_min(s, l);
+  memcpy(s->str+s->len, c, l);
+  s->len += l;
+}
+
+void string_append(string* a, string* b) {
+  if (a->cap < a->len + b->len) string_grow_min(a, b->len);
+  memcpy(a->str+a->len, b->str, b->len);
+  a->len += b->len;
+}
+
+string string_slice(string* s, size_t front, size_t back) {
+  assert(front < back);
+  assert(front < s->len);
+  assert(back < s->len);
+  int len = back - front;
+  string res = new_string_sized(len);
+  res.len = len;
+  memcpy(res.str, s->str+front, len);
+  return res;
+}
+
+bool string_compare(string* a, string* b) {
+  if (a->len != b->len) return false;
+  return strncmp(a->str, b->str, a->len) == 0;
+}
+
+// FNV-1a
+size_t string_hash(string* s) {
+  size_t hash = 2166136261;
+
+  for (int i = 0; i < s->len; i++) {
+    hash ^= s->str[i];
+    hash *= 16777619;
+  }
+
+  return hash;
+}
+
+///// list functions
+
+///// list is a list with a length and on-demand growing/shrinking
+
+#define LIST(type) \
+typedef struct list_##type { \
+  size_t len; \
+  size_t cap; \
+  type* data; \
+} list_##type; \
+ \
+list_##type new_list_sized_##type(size_t size) { \
+  list_##type l; \
+  l.len = 0; \
+  l.cap = size; \
+  l.data = calloc(size, sizeof(type)); \
+  return l; \
+} \
+ \
+list_##type new_list_##type() { \
+  return new_list_sized_##type(DEFAULT_LIST_SIZE); \
+} \
+ \
+void free_list_##type(list_##type l) { \
+  free(l.data); \
+} \
+ \
+void list_grow_##type(list_##type* l) { \
+  if (l->cap == 0) l->cap = DEFAULT_LIST_SIZE; \
+  else l->cap *= GROWTH_FACTOR; \
+  l->data = realloc(l->data, l->cap*sizeof(type)); \
+} \
+ \
+void list_shrink_##type(list_##type* l) { \
+  l->cap /= GROWTH_FACTOR; \
+  l->data = realloc(l->data, l->cap*sizeof(type)); \
+} \
+ \
+void list_push_##type(list_##type* l, type elem) { \
+  if (l->len == l->cap) list_grow_##type(l); \
+  l->data[l->len] = elem; \
+  l->len++; \
+} \
+ \
+type list_pop_##type(list_##type* l) { \
+  if (l->len*GROWTH_FACTOR < l->cap) list_shrink_##type(l); \
+  return l->data[--l->len]; \
+} \
+ \
+type list_nth_##type(list_##type* l, size_t n) { \
+  assert(n >= 0); \
+  assert(n < l->len); \
+  return l->data[n]; \
+} \
+ \
+void list_set_nth_##type(list_##type* l, size_t n, type elem) { \
+  assert(n >= 0); \
+  assert(n < l->len); \
+  l->data[n] = elem; \
+} \
+
+///// map is a hashmap
+
+#define MAP(key_type, val_type, hash, cmp) \
+typedef struct entry_##key_type##_##val_type { \
+  key_type key; \
+  val_type val; \
+} entry_##key_type##_##val_type; \
+ \
+LIST(entry_##key_type##_##val_type); \
+LIST(list_entry_##key_type##_##val_type); \
+LIST(key_type); \
+LIST(val_type); \
+ \
+typedef struct map_##key_type##_##val_type { \
+  list_list_entry_##key_type##_##val_type entries; \
+  size_t size; \
+} map_##key_type##_##val_type; \
+ \
+map_##key_type##_##val_type new_map_##key_type##_##val_type(size_t size) { \
+  int i; \
+  map_##key_type##_##val_type m;\
+  m.entries = \
+    new_list_sized_list_entry_##key_type##_##val_type(size); \
+  for (i = 0; i < size; i++) list_push_list_entry_##key_type##_##val_type(&m.entries, new_list_entry_##key_type##_##val_type()); \
+  m.size = size; \
+  return m; \
+} \
+ \
+void free_map_##key_type##_##val_type(map_##key_type##_##val_type m) { \
+  free_list_list_entry_##key_type##_##val_type(m.entries); \
+} \
+ \
+void map_put_##key_type##_##val_type(map_##key_type##_##val_type* m, key_type key, val_type val) { \
+  size_t hashed = hash(&key) % m->size; \
+  entry_##key_type##_##val_type e; \
+  e.key = key; \
+  e.val = val; \
+  list_entry_##key_type##_##val_type bucket = \
+    list_nth_list_entry_##key_type##_##val_type(&m->entries, hashed); \
+  list_push_entry_##key_type##_##val_type(&bucket, e); \
+  list_set_nth_list_entry_##key_type##_##val_type(&m->entries, hashed, bucket);\
+} \
+ \
+val_type map_get_##key_type##_##val_type(map_##key_type##_##val_type* m, key_type key, val_type dflt) { \
+  int i; \
+  size_t hashed = hash(&key) % m->size; \
+  list_entry_##key_type##_##val_type bucket = \
+    list_nth_list_entry_##key_type##_##val_type(&m->entries, hashed); \
+ \
+  for (i = 0; i < bucket.len; i++) { \
+    entry_##key_type##_##val_type e = list_nth_entry_##key_type##_##val_type(&bucket, i); \
+    if (cmp(&key, &e.key)) return e.val; \
+  } \
+ \
+  return dflt; \
+} \
+ \
+list_##key_type map_keys_##key_type##_##val_type(map_##key_type##_##val_type* m) { \
+  int i, j; \
+  list_entry_##key_type##_##val_type bucket; \
+  list_##key_type res = new_list_##key_type(); \
+  list_list_entry_##key_type##_##val_type entries = m->entries; \
+ \
+  for (i = 0; i < entries.len; i++) { \
+    bucket = list_nth_list_entry_##key_type##_##val_type(&entries, i); \
+    for (j = 0; j < bucket.len; j++) { \
+      list_push_##key_type(&res, list_nth_entry_##key_type##_##val_type(&bucket, j).key); \
+    } \
+  } \
+ \
+  return res; \
+} \
+ \
+list_##val_type map_vals_##key_type##_##val_type(map_##key_type##_##val_type* m) { \
+  int i, j; \
+  list_entry_##key_type##_##val_type bucket; \
+  list_##val_type res = new_list_##val_type(); \
+  list_list_entry_##key_type##_##val_type entries = m->entries; \
+ \
+  for (i = 0; i < entries.len; i++) { \
+    bucket = list_nth_list_entry_##key_type##_##val_type(&entries, i); \
+    for (j = 0; j < bucket.len; j++) { \
+      list_push_##val_type(&res, list_nth_entry_##key_type##_##val_type(&bucket, j).val); \
+    } \
+  } \
+ \
+  return res; \
+} \
+ \
+list_entry_##key_type##_##val_type map_entries_##key_type##_##val_type(map_##key_type##_##val_type* m) { \
+  int i, j; \
+  list_entry_##key_type##_##val_type bucket; \
+  list_entry_##key_type##_##val_type res = new_list_entry_##key_type##_##val_type(); \
+  list_list_entry_##key_type##_##val_type entries = m->entries; \
+ \
+  for (i = 0; i < entries.len; i++) { \
+    bucket = list_nth_list_entry_##key_type##_##val_type(&entries, i); \
+    for (j = 0; j < bucket.len; j++) { \
+      list_push_entry_##key_type##_##val_type( \
+        &res, \
+        list_nth_entry_##key_type##_##val_type(&bucket, j) \
+      ); \
+    } \
+  } \
+ \
+  return res; \
+} \
+
+// Config: a simple configuration language
+
+// Types: a config type and a config value type
+
+typedef struct config config;
+struct list_config_value;
+
+typedef struct config_value {
+  char tag;
+  union {
+    config* section;
+    string s;
+    double d;
+    struct list_config_value* l;
+  };
+} config_value;
+
+config_value zero_config_value = {0};
+
+MAP(string, config_value, string_hash, string_compare);
+
+struct config {
+  map_string_config_value values;
+};
+
+#define config_value_section 1
+#define config_value_string 2
+#define config_value_number 3
+#define config_value_list 4
+
+//// Functions
+
+////// config value functions
+
+bool config_value_compare(config_value* a, config_value* b) {
+  if (a->tag != b->tag) return false;
+  switch (a->tag) {
+    case config_value_section:
+      return false;
+      //return map_compare(&a->section->values, &b->section->values);
+    case config_value_string:
+      return string_compare(&a->s, &b->s);
+    case config_value_number:
+      return a->d == b->d;
+    case config_value_list:
+      return false;
+      //return list_compare(&a->l, &b->l, config_value_compare);
+  }
+  return false;
+}
+
+string config_str(config* c, unsigned int indent);
+
+string config_value_str(config_value* c, unsigned int indent) {
+  int i, j;
+  char tmp[128];
+  string sub;
+  string res = new_string();
+  config_value val;
+
+  switch (c->tag) {
+    case config_value_section:
+      string_cappend(&res, "\n");
+      sub = config_str(c->section, indent+2);
+      string_append(&res, &sub);
+      return res;
+    case config_value_string:
+      string_cappend(&res, "\"");
+      string_append(&res, &c->s);
+      string_cappend(&res, "\"");
+      break;
+    case config_value_number:
+      snprintf(tmp, 128, "%lf", c->d);
+      string_cappend(&res, tmp);
+      break;
+    case config_value_list:
+      for (i = 0; i < c->l->len; i++) {
+        string_cappend(&res, "\n");
+        for (j = 0; j < indent; j++) string_cappend(&res, " ");
+        string_cappend(&res, "  - ");
+        val = list_nth_config_value(c->l, i);
+        sub = config_value_str(&val, 0);
+        string_append(&res, &sub);
+        free_string(sub);
+      }
+  }
+  return res;
+}
+
+config_value config_section(config* section) {
+  config_value res;
+  res.tag = config_value_section;
+  res.section = section;
+  return res;
+}
+
+config_value config_string(string s) {
+  config_value res;
+  res.tag = config_value_string;
+  res.s = s;
+  return res;
+}
+
+config_value config_number(double d) {
+  config_value res;
+  res.tag = config_value_number;
+  res.d = d;
+  return res;
+}
+
+config_value config_list(list_config_value* l) {
+  config_value res;
+  res.tag = config_value_list;
+  res.l = l;
+  return res;
+}
+
+////// config functions
+
+config new_config() {
+  config c;
+  c.values = new_map_string_config_value(1024);
+  return c;
+}
+
+string config_str(config* c, unsigned int indent) {
+  int i, j;
+  string key;
+  config_value val;
+  list_string keys = map_keys_string_config_value(&c->values);
+  string res = new_string();
+  string tmp;
+
+  for (i = 0; i < keys.len; i++) {
+    key = list_nth_string(&keys, i);
+    for (j = 0; j < indent; j++) string_cappend(&res, " ");
+    string_append(&res, &key);
+    string_cappend(&res, " ");
+    val = map_get_string_config_value(&c->values, key, zero_config_value);
+    tmp = config_value_str(&val, indent);
+    string_append(&res, &tmp);
+    free_string(tmp);
+    string_cappend(&res, "\n");
+  }
+
+  return res;
+}
+
+void config_add_section(config* c, string label, config* section) {
+  assert(c != section && "cannot nest section in itself");
+  map_put_string_config_value(&c->values, label, config_section(section));
+}
+
+void config_add_string(config* c, string label, string s) {
+  map_put_string_config_value(&c->values, label, config_string(s));
+}
+
+void config_add_number(config* c, string label, double d) {
+  map_put_string_config_value(&c->values, label, config_number(d));
+}
+
+void config_add_list(config* c, string label, list_config_value* l) {
+  map_put_string_config_value(&c->values, label, config_list(l));
+}
diff --git a/examples/nested_simple.c b/examples/nested_simple.c
new file mode 100644
index 0000000..5d3c3e1
--- /dev/null
+++ b/examples/nested_simple.c
@@ -0,0 +1,26 @@
+#include "../cfg.h"
+
+int main() {
+  config c = new_config();
+  string key;
+  config_add_number(&c, string_from_cstr("mynum"), 42);
+  config_add_string(&c, string_from_cstr("mystring"), string_from_cstr("cfg is pretty awesome"));
+  list_config_value l = new_list_config_value();
+  for (int i = 0; i < 10; i += 2) {
+    config_value v = config_number(i);
+    list_push_config_value(&l, v);
+  }
+  config_add_list(&c, string_from_cstr("mylist"), &l);
+  config sub = new_config();
+  config_add_number(&sub, string_from_cstr("mysecondnum"), 23);
+  config_add_string(&sub, string_from_cstr("mysecondstring"), string_from_cstr("inner"));
+  config_add_section(&c, string_from_cstr("mysection"), &sub);
+
+  string s = config_str(&c, 0);
+  char* cstr = string_cstr(&s);
+
+  printf("%s\n", cstr);
+  free_string(s);
+  free(cstr);
+  return 0;
+}