bshell: re-organise build into three separate components

bshell: the front-end binary
bshell.runtime: contains the parser, compiler, and classes needed to run bshell scripts
bshell.core: contains the builtin commandlets and aliases

bshell.runtime/compile/state.c

@@ -0,0 +1,66 @@
+#include "compile-node.h"
+
+extern const struct compile_state_type normal_state;
+static const struct compile_state_type *state_types[] = {
+	[COMPILE_NORMAL] = &normal_state,
+};
+static const size_t nr_state_types = sizeof state_types / sizeof state_types[0];
+
+struct compile_state *compile_push_state(
+	struct compile_ctx *ctx,
+	enum compile_state_type_id state_type_id)
+{
+	if (state_type_id >= nr_state_types) {
+		return NULL;
+	}
+
+	const struct compile_state_type *state_type = state_types
+		[state_type_id];
+	if (!state_type) {
+		return NULL;
+	}
+
+	struct compile_state *state = malloc(state_type->s_size);
+	if (!state) {
+		return NULL;
+	}
+
+	state->s_type = state_type;
+	state->s_depth = ctx->c_depth;
+	fx_queue_push_back(&ctx->c_state, &state->s_entry);
+
+	if (state_type->s_compile_begin) {
+		state_type->s_compile_begin(ctx);
+	}
+
+	return state;
+}
+
+void compile_pop_state(struct compile_ctx *ctx)
+{
+	struct compile_state *state = compile_get_state(ctx);
+	if (!state) {
+		return;
+	}
+
+	if (!fx_queue_prev(&state->s_entry)) {
+		return;
+	}
+
+	if (state->s_type->s_compile_end) {
+		state->s_type->s_compile_end(ctx);
+	}
+
+	fx_queue_pop_back(&ctx->c_state);
+	free(state);
+}
+
+struct compile_state *compile_get_state(const struct compile_ctx *ctx)
+{
+	fx_queue_entry *entry = fx_queue_last(&ctx->c_state);
+	if (!entry) {
+		return NULL;
+	}
+
+	return fx_unbox(struct compile_state, entry, s_entry);
+}