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Diffstat (limited to 'src/describe.c')
| -rw-r--r-- | src/describe.c | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/src/describe.c b/src/describe.c new file mode 100644 index 00000000..5ddbf7d0 --- /dev/null +++ b/src/describe.c @@ -0,0 +1,266 @@ +/* + Copyright 2011-2020 David Robillard <d@drobilla.net> + + Permission to use, copy, modify, and/or distribute this software for any + purpose with or without fee is hereby granted, provided that the above + copyright notice and this permission notice appear in all copies. + + THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +*/ + +#include "cursor.h" +#include "model.h" +#include "world.h" + +// Define the types used in the hash interface for more type safety +#define ZIX_HASH_KEY_TYPE const SerdNode +#define ZIX_HASH_RECORD_TYPE const SerdNode + +#include "serd/serd.h" +#include "zix/common.h" +#include "zix/digest.h" +#include "zix/hash.h" + +#include <assert.h> +#include <stdbool.h> +#include <stdlib.h> + +typedef enum { NAMED, ANON_S, ANON_O, LIST_S, LIST_O } NodeStyle; + +static SerdStatus +write_range_statement(const SerdSink* sink, + const SerdModel* model, + ZixHash* list_subjects, + unsigned depth, + SerdStatementFlags flags, + const SerdStatement* statement); + +static NodeStyle +get_node_style(const SerdModel* const model, const SerdNode* const node) +{ + if (serd_node_type(node) != SERD_BLANK) { + return NAMED; // Non-blank node can't be anonymous + } + + const size_t n_as_object = serd_model_count(model, NULL, NULL, node, NULL); + if (n_as_object > 1) { + return NAMED; // Blank node referred to several times + } + + if (serd_model_count(model, node, model->world->rdf_first, NULL, NULL) == 1 && + serd_model_count(model, node, model->world->rdf_rest, NULL, NULL) == 1 && + !serd_model_ask(model, NULL, model->world->rdf_rest, node, NULL)) { + return n_as_object == 0 ? LIST_S : LIST_O; + } + + return n_as_object == 0 ? ANON_S : ANON_O; +} + +static const SerdNode* +identity(const SerdNode* const record) +{ + return record; +} + +static ZixHashCode +ptr_hash(const SerdNode* const ptr) +{ + return zix_digest(0u, &ptr, sizeof(SerdNode*)); +} + +static bool +ptr_equals(const SerdNode* const a, const SerdNode* const b) +{ + return *(const void* const*)a == *(const void* const*)b; +} + +static SerdStatus +write_pretty_range(const SerdSink* const sink, + const unsigned depth, + const SerdModel* const model, + SerdCursor* const range) +{ + ZixHash* const list_subjects = zix_hash_new(identity, ptr_hash, ptr_equals); + SerdStatus st = SERD_SUCCESS; + + while (!st && !serd_cursor_is_end(range)) { + const SerdStatement* const statement = serd_cursor_get(range); + assert(statement); + + if (!(st = write_range_statement( + sink, model, list_subjects, depth, 0, statement))) { + st = serd_cursor_advance(range); + } + } + + zix_hash_free(list_subjects); + + return st > SERD_FAILURE ? st : SERD_SUCCESS; +} + +static SerdStatus +write_list(const SerdSink* const sink, + const SerdModel* const model, + ZixHash* const list_subjects, + const unsigned depth, + SerdStatementFlags flags, + const SerdNode* object, + const SerdNode* const graph) +{ + const SerdWorld* const world = model->world; + const SerdNode* const rdf_first = world->rdf_first; + const SerdNode* const rdf_rest = world->rdf_rest; + const SerdNode* const rdf_nil = world->rdf_nil; + SerdStatus st = SERD_SUCCESS; + + const SerdStatement* fs = + serd_model_get_statement(model, object, rdf_first, NULL, graph); + + assert(fs); // Shouldn't get here if it doesn't at least have an rdf:first + + while (!st && !serd_node_equals(object, rdf_nil)) { + // Write rdf:first statement for this node + if ((st = write_range_statement( + sink, model, list_subjects, depth, flags, fs))) { + return st; + } + + // Get rdf:rest statement + const SerdStatement* const rs = + serd_model_get_statement(model, object, rdf_rest, NULL, graph); + + if (!rs) { + // Terminate malformed list with missing rdf:rest + return serd_sink_write(sink, 0, object, rdf_rest, rdf_nil, graph); + } + + // Terminate if the next node has no rdf:first + const SerdNode* const next = serd_statement_object(rs); + if (!(fs = serd_model_get_statement(model, next, rdf_first, NULL, graph))) { + return serd_sink_write(sink, 0, object, rdf_rest, rdf_nil, graph); + } + + // Write rdf:next statement and move to the next node + st = serd_sink_write_statement(sink, 0, rs); + object = next; + flags = 0u; + } + + return st; +} + +static bool +skip_range_statement(const SerdModel* const model, + const SerdStatement* const statement) +{ + const SerdNode* const subject = serd_statement_subject(statement); + const NodeStyle subject_style = get_node_style(model, subject); + const SerdNode* const predicate = serd_statement_predicate(statement); + + if (subject_style == ANON_O || subject_style == LIST_O) { + return true; // Skip subject that will be inlined elsewhere + } + + if (subject_style == LIST_S && + (serd_node_equals(predicate, model->world->rdf_first) || + serd_node_equals(predicate, model->world->rdf_rest))) { + return true; // Skip list statement that write_list will handle + } + + return false; +} + +static SerdStatus +write_range_statement(const SerdSink* const sink, + const SerdModel* const model, + ZixHash* const list_subjects, + const unsigned depth, + SerdStatementFlags flags, + const SerdStatement* SERD_NONNULL statement) +{ + const SerdNode* const subject = serd_statement_subject(statement); + const NodeStyle subject_style = get_node_style(model, subject); + const SerdNode* const object = serd_statement_object(statement); + const NodeStyle object_style = get_node_style(model, object); + const SerdNode* const graph = serd_statement_graph(statement); + SerdStatus st = SERD_SUCCESS; + + if (subject_style == ANON_S) { // Write anonymous subject like "[] p o" + flags |= SERD_EMPTY_S; + } + + if (depth == 0u) { + if (skip_range_statement(model, statement)) { + return SERD_SUCCESS; // Skip subject that will be inlined elsewhere + } + + if (subject_style == LIST_S) { + // First write inline list subject, which this statement will follow + if (zix_hash_insert(list_subjects, subject) != ZIX_STATUS_EXISTS) { + st = write_list( + sink, model, list_subjects, 2, SERD_LIST_S, subject, graph); + } + } + } + + if (st) { + return st; + } + + if (object_style == ANON_O) { // Write anonymous object like "[ ... ]" + SerdCursor* const iter = serd_model_find(model, object, NULL, NULL, NULL); + + flags |= SERD_ANON_O; + if (!(st = serd_sink_write_statement(sink, flags, statement))) { + if (!(st = write_pretty_range(sink, depth + 1, model, iter))) { + st = serd_sink_write_end(sink, object); + } + } + + serd_cursor_free(iter); + + } else if (object_style == LIST_O) { // Write list object like "( ... )" + flags |= SERD_LIST_O; + if (!(st = serd_sink_write_statement(sink, flags, statement))) { + st = write_list(sink, model, list_subjects, depth + 1, 0, object, graph); + } + + } else { + st = serd_sink_write_statement(sink, flags, statement); + } + + return st; +} + +SerdStatus +serd_describe_range(const SerdCursor* const range, + const SerdSink* sink, + const SerdDescribeFlags flags) +{ + SerdStatus st = SERD_SUCCESS; + + if (serd_cursor_is_end(range)) { + return st; + } + + SerdCursor copy = *range; + + if (flags & SERD_NO_INLINE_OBJECTS) { + const SerdStatement* statement = NULL; + while (!st && (statement = serd_cursor_get(©))) { + if (!(st = serd_sink_write_statement(sink, 0, statement))) { + st = serd_cursor_advance(©); + } + } + } else { + st = write_pretty_range(sink, 0, range->model, ©); + } + + return st; +} |