Lay Pure out as a core with the parts selected around it

The app model, the tree store and the HTTP host lived in
prototypes/connections among the earlier document runtime, the store was
known only by its format's name, and Vega compiled six Pure sources by path.
Now, as the README's principle has it:

  core/   runtime, flow and the app model (module*.c), with what the core
          asks of storage (state.h, store.h)
  store/  the tree store (PURETRE3, PUREREC1)
  serve/  pure-serve: HTTP host, outbound delivery, JSON in place
  cli/    pure-run, pure-edit-module

A top-level make builds libpure.a (app model and store, for hosts to link)
and the hosts; make check runs the store's and the app model's tests. The
earlier runtime still builds from prototypes/connections against core/ and
store/ (check, check-tree and check-core pass). Design 009 records the rule:
parts by role behind libraries; git repositories split by coupling, so the
store stays here while its contract moves with the core, and Vega stays apart.

1 files changed, 88 insertions, 0 deletions

diff --git a/core/module-store.c b/core/module-store.c
new file mode 100644
index 0000000..7e759fd
--- /dev/null
+++ b/core/module-store.c
@@ -0,0 +1,88 @@
+#include "module-store.h"
+
+static PureResult open_document(void *context, uint32_t collection, const char *key,
+                                void **document, int64_t *revision) {
+    (void)collection; /* v2 modules have one collection: the store's key space */
+    PureDraft *draft;
+    PureResult result = pure_draft_open(context, key, &draft);
+    if (result != PURE_OK) return result;
+    pure_draft_hold(draft, true); /* values read in the event stay readable */
+    *document = draft;
+    *revision = pure_draft_revision(draft);
+    return PURE_OK;
+}
+
+static PureVersion version(void *context, void *document) {
+    (void)context;
+    return pure_draft_version(document);
+}
+
+static PureResult read(void *context, void *document, PureVersion at, size_t offset, size_t length,
+                       bool (*visit)(void *, PureSpan), void *visit_context) {
+    (void)context;
+    return pure_draft_read_version(document, at, offset, length, visit, visit_context);
+}
+
+static PureResult splice(void *context, void *document, size_t offset, size_t remove, PureSpan insert) {
+    (void)context;
+    return pure_draft_splice(document, offset, remove, insert);
+}
+
+static PureResult commit(void *context, void *document, int64_t *revision) {
+    (void)context;
+    return pure_draft_commit(document, revision);
+}
+
+static void close_document(void *context, void *document) {
+    (void)context;
+    pure_draft_close(document);
+}
+
+static PureResult state(void *context, const char *name, PureDraft **out) {
+    return pure_state_open(context, name, out);
+}
+
+enum { SAVED = PURE_APP_PENDING + 2 * PURE_MODULE_STATES + 1 };
+
+/* The documents and the app's changed states in one tree commit. */
+static PureResult save(void *context, void *const *documents, size_t document_count, PureDraft *const *states,
+                       size_t count, int64_t *revisions) {
+    (void)context;
+    PureDraft *drafts[SAVED] = {0};
+    int64_t all[SAVED] = {0};
+    if (document_count > PURE_APP_PENDING || count > SAVED - document_count) return PURE_LIMIT;
+    for (size_t i = 0; i < document_count; ++i) drafts[i] = documents[i];
+    for (size_t i = 0; i < count; ++i) drafts[document_count + i] = states[i];
+    PureResult result = pure_draft_commit_all(drafts, document_count + count, all);
+    for (size_t i = 0; i < document_count; ++i) revisions[i] = all[i];
+    return result;
+}
+
+/* Through a store handle: documents and states share its mapping. */
+static PureResult open_handle_document(void *context, uint32_t collection, const char *key, void **document,
+                                       int64_t *revision) {
+    (void)collection;
+    PureDraft *draft;
+    PureResult result = pure_store_draft(context, key, &draft);
+    if (result != PURE_OK) return result;
+    pure_draft_hold(draft, true);
+    *document = draft;
+    *revision = pure_draft_revision(draft);
+    return PURE_OK;
+}
+
+static PureResult handle_state(void *context, const char *name, PureDraft **out) {
+    return pure_store_state(context, name, out);
+}
+
+PureData pure_store_data(PureStore *store) {
+    return (PureData){.context = store, .open = open_handle_document, .version = version, .read = read,
+                      .splice = splice, .commit = commit, .close = close_document, .state = handle_state,
+                      .save = save};
+}
+
+PureData pure_tree_data(const char *path) {
+    return (PureData){.context = (void *)path, .open = open_document, .version = version,
+                      .read = read, .splice = splice, .commit = commit, .close = close_document,
+                      .state = state, .save = save};
+}