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Diffstat (limited to 'src/pbg.h')
| -rw-r--r--[l---------] | src/pbg.h | 240 |
1 files changed, 239 insertions, 1 deletions
diff --git a/src/pbg.h b/src/pbg.h index 36a1da6..98a3370 120000..100644 --- a/src/pbg.h +++ b/src/pbg.h @@ -1 +1,239 @@ -../pbg/pbg.h
\ No newline at end of file +#ifndef __PBG_H__ +#define __PBG_H__ + +/********************************************************* + * * + * Prefix Boolean Grammar (PBG), a lightweight C library * + * By Tyler J. Daddio, November 2018 * + * * + *********************************************************/ + +/* Used to suppress compiler warnings for intentionally unused arguments. This + * isn't as foolproof as GCC's unused attribute, but it is not compiler- + * dependent, which is just dandy. */ +#define PBG_UNUSED(x) (void)(x) + +/* Used to represent the result of an expression evaluation. */ +#define PBG_FALSE 0 +#define PBG_TRUE 1 +#define PBG_ERROR -1 + +/***************************** + * * + * EXPRESSION REPRESENTATION * + * * + *****************************/ + +/** + * Types of PBG fields. + */ +typedef enum { + PBG_NULL, /* NULL: Unknown field type */ + + /* Type literals. */ + PBG_MIN_LT_TP, + PBG_LT_TP_DATE, /* DATE TYPE literal */ + PBG_LT_TP_BOOL, /* TRUE/FALSE TYPE literal */ + PBG_LT_TP_NUMBER, /* NUMBER TYPE literal */ + PBG_LT_TP_STRING, /* STRING TYPE literal */ + /* Add more TYPE literals here. */ + PBG_MAX_LT_TP, + + /* Literals. */ + PBG_MIN_LT, + PBG_LT_TRUE, /* TRUE literal */ + PBG_LT_FALSE, /* FALSE literal */ + PBG_LT_NUMBER, /* NUMBER literal */ + PBG_LT_STRING, /* STRING literal */ + PBG_LT_DATE, /* DATE literal */ + PBG_LT_VAR, /* VARiable literal */ + /* Add more literals here. */ + PBG_MAX_LT, + + /* Operators. */ + PBG_MIN_OP, + PBG_OP_NOT, /* ! NOT */ + PBG_OP_AND, /* & AND */ + PBG_OP_OR, /* | OR */ + PBG_OP_EQ, /* = EQUAL */ + PBG_OP_LT, /* < LESS THAN */ + PBG_OP_GT, /* > GREATER THAN */ + PBG_OP_EXST, /* ? EXISTS */ + PBG_OP_NEQ, /* != NOT EQUAL */ + PBG_OP_LTE, /* <= LESS THAN OR EQUAL TO */ + PBG_OP_GTE, /* >= GREATER THAN OR EQUAL TO */ + PBG_OP_TYPE, /* @ TYPE OF */ + /* Add more operators here. */ + PBG_MAX_OP +} pbg_field_type; + +/** + * This struct represents a PBG field. A field can be either a literal or an + * operator. This is determined by its type. For operators, the data pointer + * describes a list of pointers to other fields in the abstract syntax tree. + * For constants, it describes data relevant to the field type. + */ +typedef struct { + pbg_field_type _type; /* Node type, determines the type/size of data. */ + int _int; /* Type determines what this is used for! */ + void* _data; /* Arbitrary data! */ +} pbg_field; + +/** + * This struct represents a PBG expression. There are two arrays in this + * representation: one for constants, and one for variables. Both types are + * represented by fields. + */ +typedef struct { + pbg_field* _constants; /* Constants. */ + pbg_field* _variables; /* Variables. */ + int _numconst; /* Number of constants. */ + int _numvars; /* Number of variables. */ +} pbg_expr; + + +/************************ + * * + * ERROR REPRESENTATION * + * * + ************************/ + +/** + * Type specifiers for all possible PBG errors. + */ +typedef enum { + PBG_ERR_NONE, + PBG_ERR_ALLOC, + PBG_ERR_STATE, + PBG_ERR_SYNTAX, + PBG_ERR_UNKNOWN_TYPE, + PBG_ERR_OP_ARITY, + PBG_ERR_OP_ARG_TYPE +} pbg_error_type; + +/** + * Represents a PBG error. Errors may be generated during parsing and + * evaluation and should be checked by the caller. + */ +typedef struct { + pbg_error_type _type; /* Error type. */ + int _line; /* Line of file where error occurred. */ + char* _file; /* File in which error occurred. */ + int _int; /* Type determines what this is used for! */ + void* _data; /* Data to be included with error report. */ +} pbg_error; + + +/*************** + * * + * EXPRESSIONS * + * * + ***************/ + +/** + * Parses the string as a boolean expression in Prefix Boolean Grammar. + * @param e PBG expression instance to initialize. + * @param err Container to store error, if any occurs. + * @param str String to parse. This must be terminated with '\0'. + */ +void pbg_parse(pbg_expr* e, pbg_error* err, char* str); + +/** + * Parses the string as a boolean expression in Prefix Boolean Grammar. + * @param e PBG expression instance to initialize. + * @param err Container to store error, if any occurs. + * @param str String to parse. + * @param n Length of the string. + */ +void pbg_parse_n(pbg_expr* e, pbg_error* err, char* str, int n); + +/** + * Evaluates the PBG expression with the provided assignments. + * @param e PBG expression to evaluate. + * @param err Container to store error, if any occurs. + * @param dict Dictionary used to resolve VAR names. + * @return 1 if the PBG expression evaluates to true with the given dictionary. + * 0 otherwise. + */ +int pbg_evaluate(pbg_expr* e, pbg_error* err, pbg_field (*dict)(char*, int)); + +/** + * Destroys the PBG expression instance and frees all associated resources. + * This function does not free the provided pointer. + * @param e PBG expression to destroy. + */ +void pbg_free(pbg_expr* e); + + +/************** + * * + * FIELDS * + * * + **************/ + +/** + * Makes a field representing a DATE. + * @param year Year of the date. + * @param month Month of the date. + * @param day Day of the date. + * @return a new DATE field. + */ +pbg_field pbg_make_date(int year, int month, int day); + +/** + * Makes a field representing a BOOL. + * @param truth Truth value of the new BOOL. + * @return a new BOOL field. + */ +pbg_field pbg_make_bool(int truth); + +/** + * Makes a field representing a NUMBER. + * @param value Numeric value of the NUMBER. + * @return a new NUMBER field. + */ +pbg_field pbg_make_number(double value); + +/** + * Makes a field representing a STRING. + * @param value Value of the STRING. + * @return a new STRING field. + */ +pbg_field pbg_make_string(char* str); + +/** + * Makes a field representing NULL. + * @return a new NULL field. + */ +pbg_field pbg_make_null(void); + + +/*************** + * * + * ERRORS * + * * + ***************/ + +/** + * Checks if the given error has been initialized with error data. + * @param err Error to check. + * @return 1 if the given error has been initialized, 0 otherwise. + */ +int pbg_iserror(pbg_error* err); + +/** + * Prints a human-readable representation of the given pbg_error to the + * standard output. + * @param err Error to print. + */ +void pbg_error_print(pbg_error* err); + +/** + * Frees resources being used by the given error, if any. This function does + * not free the provided pointer. + * @param e PBG error to clean up. + */ +void pbg_error_free(pbg_error* e); + + +#endif /* __PBG_H__ */ |