Skip to content

[parser.c] simplify json_value_completed transition #995

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
byroot merged 1 commit into from
Jun 5, 2026
+14 −18
Merged

[parser.c] simplify json_value_completed transition #995

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
32 changes: 14 additions & 18 deletions ext/json/ext/parser/parser.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -345,22 +345,25 @@ static void rvalue_stack_eagerly_release(VALUE handle)
#define JSON_FRAME_STACK_INITIAL_CAPA 32

enum json_frame_type {
JSON_FRAME_ROOT,
JSON_FRAME_ARRAY,
JSON_FRAME_OBJECT,
JSON_FRAME_ROOT, // == JSON_PHASE_DONE
JSON_FRAME_ARRAY, // == JSON_PHASE_ARRAY_COMMA
JSON_FRAME_OBJECT, // = JSON_PHASE_OBJECT_COMMA
};

// Where a frame is within its container's grammar. This is the entirety of the
// parser's "what to do next" state: json_parse_any dispatches on the top
// frame's phase and holds no resume state in C locals, so a parse can stop at
// any value boundary and be resumed purely from the (persistable) frame stack.
//
// The first three phases are deliberately equal to the corresponding json_frame_type
// to simplify the transition of phase in json_value_completed.
enum json_frame_phase {
JSON_PHASE_DONE = JSON_FRAME_ROOT, // root only: the document value has been parsed
JSON_PHASE_ARRAY_COMMA = JSON_FRAME_ARRAY, // after a value: expecting ',' or the closing ']'
JSON_PHASE_OBJECT_COMMA = JSON_FRAME_OBJECT, // after a value: expecting ',' or the closing '}'
JSON_PHASE_VALUE, // expecting a value (document root, array element, or object value after ':')
JSON_PHASE_ARRAY_COMMA, // after a value: expecting ',' or the closing ']'
JSON_PHASE_OBJECT_KEY, // expecting a '"' key (after '{' or ',')
JSON_PHASE_OBJECT_COMMA, // after a value: expecting ',' or the closing '}'
JSON_PHASE_OBJECT_COLON, // object only: after a key, expecting ':'
JSON_PHASE_DONE, // root only: the document value has been parsed
};

typedef struct json_frame_struct {
Expand Down Expand Up @@ -1442,18 +1445,11 @@ static inline long json_frame_entry_count(const json_frame *frame, const rvalue_
// after a container close is the freshly re-exposed parent.
static inline void json_value_completed(json_frame *frame)
{
switch (frame->type) {
case JSON_FRAME_ROOT:
frame->phase = JSON_PHASE_DONE;
return;
case JSON_FRAME_ARRAY:
frame->phase = JSON_PHASE_ARRAY_COMMA;
return;
case JSON_FRAME_OBJECT:
frame->phase = JSON_PHASE_OBJECT_COMMA;
return;
}
UNREACHABLE;
JSON_ASSERT((int)JSON_PHASE_DONE == (int)JSON_FRAME_ROOT);
JSON_ASSERT((int)JSON_PHASE_ARRAY_COMMA == (int)JSON_FRAME_ARRAY);
JSON_ASSERT((int)JSON_PHASE_OBJECT_COMMA == (int)JSON_FRAME_OBJECT);

frame->phase = (enum json_frame_phase) frame->type;
}

// Parse an arbitrary JSON value iteratively. This is a state machine driven
Expand Down
Loading