grammar_context.h File Reference

Grammar Context – language switching for embedded grammars. More...

#include <stdbool.h>
#include <stdint.h>

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Data Structures
struct	GrammarContextEntry
	One level of the grammar context stack. More...
struct	GrammarModeInfo
	Describes a grammar mode that can be entered during parsing. More...

Typedefs
typedef bool(*	ContextSwitchCallback) (GrammarMode prev_mode, GrammarMode new_mode, void *user_data)
	Called when a context switch occurs.
typedef struct GrammarContextStack	GrammarContextStack
	Opaque grammar context stack handle.

Enumerations
enum	GrammarMode {   MODE_SQL = 0 , MODE_XQUERY , MODE_XPATH , MODE_EDN ,   MODE_JSON , MODE_CUSTOM , MODE_COUNT_ }
	Grammar mode identifiers. More...

Functions
bool	grammar_context_close_bracket (GrammarContextStack *stack)
	Notify the context stack that a bracket/parenthesis was closed.
GrammarContextStack *	grammar_context_create (ParserSnapshot *root_snapshot)
	Create a context stack with the given root grammar snapshot.
GrammarMode	grammar_context_current_mode (const GrammarContextStack *stack)
	Return the current grammar mode.
ParserSnapshot *	grammar_context_current_snapshot (const GrammarContextStack *stack)
	Return the snapshot for the current (topmost) grammar context.
uint32_t	grammar_context_depth (const GrammarContextStack *stack)
	Return the current nesting depth (0 = root).
void	grammar_context_destroy (GrammarContextStack *stack)
	Destroy the context stack and release all snapshot references.
bool	grammar_context_detect_exit (GrammarContextStack *stack, int token_code)
	Detect whether the current embedded context should end.
bool	grammar_context_detect_switch (GrammarContextStack *stack, int token_code, const char *lexeme, uint32_t offset)
	Detect whether a context switch should occur.
bool	grammar_context_is_root_only (const GrammarContextStack *stack)
	Check if only the root grammar is active.
void	grammar_context_open_bracket (GrammarContextStack *stack)
	Notify the context stack that a bracket/parenthesis was opened.
bool	grammar_context_pop (GrammarContextStack *stack)
	Pop the current grammar context.
bool	grammar_context_push (GrammarContextStack *stack, GrammarMode mode, uint32_t offset)
	Explicitly push a grammar mode onto the context stack.
bool	grammar_context_register_mode (GrammarContextStack *stack, const GrammarModeInfo *info)
	Register a grammar mode.
void	grammar_context_set_switch_callback (GrammarContextStack *stack, ContextSwitchCallback cb, void *user_data)
	Register a callback to be invoked on context switches.

Detailed Description

Grammar Context – language switching for embedded grammars.

Manages a stack of grammar contexts to support parsing inputs that mix multiple languages (e.g., SQL with embedded XQuery expressions or EDN literals).

Each context represents an active grammar identified by a name and backed by a ParserSnapshot. When the parser encounters a boundary token (e.g., "xmlquery(", "xpath(", "{:"), it pushes a new context for the embedded language. When the embedded region ends, the context is popped and parsing resumes with the previous grammar.

Supported Modes

Mode	Description
MODE_SQL	Standard SQL (default / root)
MODE_XQUERY	XQuery embedded in xmlquery(...)
MODE_XPATH	XPath embedded in xpath(...)
MODE_EDN	EDN embedded in {: ... :}
MODE_JSON	JSON embedded literal
MODE_CUSTOM	User-defined grammar mode

Usage Example

GrammarContextStack *stack = grammar_context_create(sql_snap);
 
GrammarModeInfo xq_info = {
    .mode = MODE_XQUERY, .name = "xquery",
    .snapshot = xq_snap, .trigger_token = TK_XMLQUERY,
    .exit_token = -1,
};
grammar_context_register_mode(stack, &xq_info);
 
// During lexing:
if (grammar_context_detect_switch(stack, token, lexeme, offset)) {
    // context was pushed, new snapshot is active
}
 
grammar_context_destroy(stack);

See also

parser.h for snapshot reference management.

Definition in file grammar_context.h.