1 files changed, 91 insertions, 0 deletions
diff --git a/prism/stringy.c b/prism/stringy.c
new file mode 100644
index 0000000000..d6f4c4a777
--- /dev/null
+++ b/prism/stringy.c
@@ -0,0 +1,91 @@
+#include "prism/internal/stringy.h"
+
+#include "prism/internal/allocator.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+/**
+ * Initialize a shared string that is based on initial input.
+ */
+void
+pm_string_shared_init(pm_string_t *string, const uint8_t *start, const uint8_t *end) {
+    assert(start <= end);
+
+    *string = (pm_string_t) {
+        .type = PM_STRING_SHARED,
+        .source = start,
+        .length = (size_t) (end - start)
+    };
+}
+
+/**
+ * Initialize an owned string that is responsible for freeing allocated memory.
+ */
+void
+pm_string_owned_init(pm_string_t *string, uint8_t *source, size_t length) {
+    *string = (pm_string_t) {
+        .type = PM_STRING_OWNED,
+        .source = source,
+        .length = length
+    };
+}
+
+/**
+ * Initialize a constant string that doesn't own its memory source.
+ */
+void
+pm_string_constant_init(pm_string_t *string, const char *source, size_t length) {
+    *string = (pm_string_t) {
+        .type = PM_STRING_CONSTANT,
+        .source = (const uint8_t *) source,
+        .length = length
+    };
+}
+
+/**
+ * Compare the underlying lengths and bytes of two strings. Returns 0 if the
+ * strings are equal, a negative number if the left string is less than the
+ * right string, and a positive number if the left string is greater than the
+ * right string.
+ */
+int
+pm_string_compare(const pm_string_t *left, const pm_string_t *right) {
+    size_t left_length = pm_string_length(left);
+    size_t right_length = pm_string_length(right);
+
+    if (left_length < right_length) {
+        return -1;
+    } else if (left_length > right_length) {
+        return 1;
+    }
+
+    return memcmp(pm_string_source(left), pm_string_source(right), left_length);
+}
+
+/**
+ * Returns the length associated with the string.
+ */
+size_t
+pm_string_length(const pm_string_t *string) {
+    return string->length;
+}
+
+/**
+ * Returns the start pointer associated with the string.
+ */
+const uint8_t *
+pm_string_source(const pm_string_t *string) {
+    return string->source;
+}
+
+/**
+ * Free the associated memory of the given string.
+ */
+void
+pm_string_cleanup(pm_string_t *string) {
+    if (string->type == PM_STRING_OWNED) {
+        xfree_sized((void *) string->source, string->length);
+    }
+}