1 files changed, 112 insertions, 0 deletions
diff --git a/src/parser.c b/src/parser.c
new file mode 100644
index 0000000..a235746
--- /dev/null
+++ b/src/parser.c
@@ -0,0 +1,112 @@
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdalign.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "errors.h"
+#include "parser.h"
+
+/* #define AST_DFLT_CAP (2048) */
+#define AST_DFLT_CAP (8)
+#define SIZE_WDTH    (sizeof(size_t) * CHAR_BIT)
+
+static struct ast_soa mk_ast_soa(void);
+static void ast_soa_resz(struct ast_soa *);
+
+struct ast_soa
+parsetoks(struct lexemes_soa toks)
+{
+	struct ast_soa ast = mk_ast_soa();
+
+	return ast;
+}
+
+struct ast_soa
+mk_ast_soa(void)
+{
+	struct ast_soa soa;
+
+	static_assert(offsetof(struct ast_soa, kinds)
+	                  < offsetof(struct ast_soa, lexemes),
+	              "KINDS is not the first field before LEXEMES");
+	static_assert(offsetof(struct ast_soa, kinds)
+	                  < offsetof(struct ast_soa, kids),
+	              "KINDS is not the first field before KIDS");
+	static_assert(AST_DFLT_CAP * sizeof(*soa.kinds) % alignof(*soa.lexemes)
+	                  == 0,
+	              "Additional padding is required to properly align LEXEMES");
+	static_assert(AST_DFLT_CAP * (sizeof(*soa.kinds) + sizeof(*soa.lexemes))
+	                      % alignof(*soa.kids)
+	                  == 0,
+	              "Additional padding is required to properly align KIDS");
+
+	soa.len = 0;
+	soa.cap = AST_DFLT_CAP;
+
+	if ((soa.kinds = malloc(soa.cap * AST_SOA_BLKSZ)) == NULL)
+		err("malloc:");
+	soa.lexemes = (void *)((char *)soa.kinds + soa.cap * sizeof(*soa.kinds));
+	soa.kids = (void *)((char *)soa.lexemes + soa.cap * sizeof(*soa.lexemes));
+
+	return soa;
+}
+
+void
+ast_soa_resz(struct ast_soa *soa)
+{
+	static_assert(offsetof(struct ast_soa, kinds)
+	                  < offsetof(struct ast_soa, lexemes),
+	              "KINDS is not the first field before LEXEMES");
+	static_assert(offsetof(struct ast_soa, kinds)
+	                  < offsetof(struct ast_soa, kids),
+	              "KINDS is not the first field before KIDS");
+	static_assert(offsetof(struct ast_soa, lexemes)
+	                  < offsetof(struct ast_soa, kids),
+	              "LEXEMES is not the second field before KIDS");
+
+	size_t ncap, pad1, pad2, newsz;
+	ptrdiff_t lexemes_off, kids_off;
+
+	lexemes_off = (char *)soa->lexemes - (char *)soa->kinds;
+	kids_off = (char *)soa->kids - (char *)soa->kinds;
+
+	/* The capacity is always going to be a power of 2, so checking for overflow
+	   becomes pretty trivial */
+	if ((soa->cap >> (SIZE_WDTH - 1)) != 0) {
+		errno = EOVERFLOW;
+		err("ast_soa_resz:");
+	}
+	ncap = soa->cap << 1;
+
+	/* Ensure that soa->lexemes is properly aligned */
+	pad1 = alignof(*soa->lexemes)
+	     - ncap * sizeof(*soa->kinds) % alignof(*soa->lexemes);
+	if (pad1 == alignof(*soa->lexemes))
+		pad1 = 0;
+
+	pad2 = alignof(*soa->kids)
+	     - (ncap * (sizeof(*soa->kinds) + sizeof(*soa->lexemes)) + pad1)
+	           % alignof(*soa->kids);
+	if (pad2 != alignof(*soa->kids))
+		pad2 = 0;
+
+	newsz = ncap * AST_SOA_BLKSZ + pad1 + pad2;
+
+	if ((soa->kinds = realloc(soa->kinds, newsz)) == NULL)
+		err("realloc:");
+
+	soa->lexemes = (void *)((char *)soa->kinds + ncap * sizeof(*soa->kinds)
+	                        + pad1);
+	soa->kids = (void *)((char *)soa->lexemes + ncap * sizeof(*soa->lexemes)
+	                     + pad2);
+
+	memmove(soa->kids, (char *)soa->kinds + kids_off,
+	        soa->len * sizeof(*soa->kids));
+	memmove(soa->lexemes, (char *)soa->kinds + lexemes_off,
+	        soa->len * sizeof(*soa->lexemes));
+
+	soa->cap = ncap;
+}