toolchain: add a program for compiling ipc interface definitions

ifc can be used to compile .if files into self-contained header-only C
libraries, which can be used to send/receive messages that conform
to the described interface.

toolchain/ifc/lex.h

@@ -0,0 +1,52 @@
+#ifndef IFC_LEX_H_
+#define IFC_LEX_H_
+
+#include "status.h"
+#include "token.h"
+
+#include <blue/core/queue.h>
+#include <blue/ds/dict.h>
+#include <blue/ds/string.h>
+#include <stdint.h>
+
+struct lex {
+	struct lex_symbol_node *lex_sym_tree;
+	struct line_source *lex_source;
+	enum status lex_status;
+
+	b_queue lex_queue;
+
+	b_string *lex_temp;
+	b_queue lex_state;
+	unsigned int lex_brace_depth;
+
+	struct file_cell lex_token_start, lex_token_end;
+};
+
+struct lex_symbol_node {
+	char s_char;
+	struct lex_token_def *s_def;
+
+	b_queue_entry s_entry;
+	b_queue s_children;
+};
+
+struct lex_token_def {
+	int id;
+	const char *name;
+	uint64_t name_hash;
+};
+
+struct token;
+struct line_source;
+
+extern struct lex *lex_create(struct line_source *src);
+extern void lex_destroy(struct lex *lex);
+
+extern enum status lex_get_status(const struct lex *lex);
+extern struct line_source *lex_get_line_source(const struct lex *lex);
+extern const struct file_cell *lex_get_cursor(const struct lex *lex);
+extern struct token *lex_peek(struct lex *lex);
+extern void lex_advance(struct lex *lex);
+
+#endif