From 267d3499232cd538530beac0cb1047ed6cf3eadc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20Krzy=C5=BCanowski?= <krzmaciek@gmail.com>
Date: Sun, 23 Feb 2025 22:51:14 +0100
Subject: [PATCH] Initial commit

---
 .gitignore           |  2 ++
 Makefile             | 35 +++++++++++++++++++++++++++++++++++
 pureoption-example.c | 15 +++++++++++++++
 pureoption.c         | 23 +++++++++++++++++++++++
 pureoption.h         | 25 +++++++++++++++++++++++++
 5 files changed, 100 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 pureoption-example.c
 create mode 100644 pureoption.c
 create mode 100644 pureoption.h

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..44d23bc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+build/
+pureoption-example
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..69bef38
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,35 @@
+CC = gcc
+CCFLAGS = -Wall
+BUILDDIR = build
+SRCS = pureoption-example.c pureoption.c
+OBJS = $(addprefix $(BUILDDIR)/, $(patsubst %.c,%.o,$(SRCS)))
+OUT = pureoption-example
+
+.PHONY: all format clean
+.PRECIOUS: $(BUILDDIR)/. $(BUILDDIR)%/.
+
+all: $(OUT)
+
+debug: CCFLAGS += -g
+debug: all
+
+$(BUILDDIR)/.:
+	mkdir -p $@
+
+$(BUILDDIR)%/.:
+	mkdir -p $@
+
+$(OUT): $(OBJS)
+	$(CC) $^ -o $(OUT) $(LDFLAGS)
+
+.SECONDEXPANSION:
+
+$(BUILDDIR)/%.o: %.c | $$(@D)/.
+	$(CC) $(CCFLAGS) -c $< -o $@
+
+format:
+	clang-format -i *.c *.h
+
+clean:
+	rm -rf $(BUILDDIR)
+	rm -f $(OUT)
diff --git a/pureoption-example.c b/pureoption-example.c
new file mode 100644
index 0000000..e854cad
--- /dev/null
+++ b/pureoption-example.c
@@ -0,0 +1,15 @@
+#include "pureoption.h"
+#include <stdio.h>
+
+int main(void) {
+  pureoption opt = pureoption_some(3);
+
+  printf("pureoption_some(3)\n");
+  printf("\thas value: %s\n", pureoption_has(opt) == 1 ? "yes" : "no");
+  printf("\tvalue: %d\n", pureoption_get(int, opt));
+
+  opt = pureoption_none();
+
+  printf("pureoption_none\n");
+  printf("\thas value: %s\n", pureoption_has(opt) == 1 ? "yes" : "no");
+}
diff --git a/pureoption.c b/pureoption.c
new file mode 100644
index 0000000..4443ed9
--- /dev/null
+++ b/pureoption.c
@@ -0,0 +1,23 @@
+#include "pureoption.h"
+#include <stddef.h>
+
+inline static pureoption __pureoption_new(bool has_value, void *value) {
+  pureoption result = {
+      .has_value = has_value,
+      .value = value,
+  };
+
+  return result;
+}
+
+pureoption _pureoption_some(void *value) {
+  return __pureoption_new(true, value);
+}
+
+pureoption pureoption_none(void) { return __pureoption_new(false, NULL); }
+
+bool pureoption_has(pureoption option) { return option.has_value; }
+
+bool pureoption_lacks(pureoption option) { return !option.has_value; }
+
+void *_pureoption_get(pureoption option) { return option.value; }
diff --git a/pureoption.h b/pureoption.h
new file mode 100644
index 0000000..fe474d6
--- /dev/null
+++ b/pureoption.h
@@ -0,0 +1,25 @@
+#ifndef PUREOPTION_H
+#define PUREOPTION_H
+
+#include <stdbool.h>
+
+#define pureoption_some(x)                                                     \
+  ({                                                                           \
+    static typeof(x) _temp = (x);                                              \
+    _pureoption_some(&_temp);                                                  \
+  })
+
+#define pureoption_get(x_type, x) *(x_type *)_pureoption_get(x)
+
+typedef struct {
+  bool has_value;
+  void *value;
+} pureoption;
+
+pureoption _pureoption_some(void *value);
+pureoption pureoption_none(void);
+bool pureoption_has(pureoption option);
+bool pureoption_lacks(pureoption option);
+void *_pureoption_get(pureoption option);
+
+#endif // PUREOPTION_H