src/cx/properties.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2024 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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/**
 * @file properties.h
 * @brief Interface for parsing data from properties files.
 * @author Mike Becker
 * @author Olaf Wintermann
 * @copyright 2-Clause BSD License
 */

#ifndef UCX_PROPERTIES_H
#define UCX_PROPERTIES_H

#include "common.h"
#include "string.h"
#include "map.h"
#include "buffer.h"

/**
 * Configures the expected characters for the properties parser.
 */
struct cx_properties_config_s {
    /**
     * The key/value delimiter that shall be used.
     * This is '=' by default.
     */
    char delimiter;

    /**
     * The first comment character.
     * This is '#' by default.
     */
    char comment1;

    /**
     * The second comment character.
     * This is not set by default.
     */
    char comment2;

    /**
     * The third comment character.
     * This is not set by default.
     */
    char comment3;

    /**
     * The character, when appearing at the end of a line, continues that line.
     * This is '\' by default.
     */
    char continuation;
};

/**
 * Typedef for the properties config.
 */
typedef struct cx_properties_config_s CxPropertiesConfig;

/**
 * Default properties configuration.
 */
CX_EXPORT extern const CxPropertiesConfig cx_properties_config_default;

/**
 * Status codes for the properties interface.
 */
enum cx_properties_status {
    /**
     * Everything is fine.
     */
    CX_PROPERTIES_NO_ERROR,
    /**
     * The input buffer does not contain more data.
     */
    CX_PROPERTIES_NO_DATA,
    /**
     * The input ends unexpectedly.
     *
     * This either happens when the last line does not terminate with a line
     * break, or when the input ends with a parsed key but no value.
     */
    CX_PROPERTIES_INCOMPLETE_DATA,
    /**
     * Not used as a status and never returned by any function.
     *
     * You can use this enumerator to check for all "good" status results
     * by checking if the status is less than @c CX_PROPERTIES_OK.
     *
     * A "good" status means that you can refill data and continue parsing.
     */
    CX_PROPERTIES_OK,
    /**
     * Input buffer is @c NULL.
     */
    CX_PROPERTIES_NULL_INPUT,
    /**
     * The line contains a delimiter but no key.
     */
    CX_PROPERTIES_INVALID_EMPTY_KEY,
    /**
     * The line contains data but no delimiter.
     */
    CX_PROPERTIES_INVALID_MISSING_DELIMITER,
    /**
     * More internal buffer was needed, but could not be allocated.
     */
    CX_PROPERTIES_BUFFER_ALLOC_FAILED,
    /**
     * A file operation failed.
     * Only for cxPropertiesLoad().
     * It is system-specific if errno is set.
     */
    CX_PROPERTIES_FILE_ERROR,
    /**
     * A map operation failed.
     * Only for cxPropertiesLoad().
     */
    CX_PROPERTIES_MAP_ERROR,
};

/**
 * Typedef for the properties status enum.
 */
typedef enum cx_properties_status CxPropertiesStatus;

/**
 * Interface for working with properties data.
 */
struct cx_properties_s {
    /**
     * The configuration.
     */
    CxPropertiesConfig config;

    /**
     * The text input buffer.
     */
    CxBuffer input;

    /**
     * Internal buffer.
     */
    CxBuffer buffer;
};

/**
 * Typedef for the properties interface.
 */
typedef struct cx_properties_s CxProperties;

/**
 * Initialize a properties interface.
 *
 * @param prop the properties interface
 * @param config the properties configuration
 * @see cxPropertiesInitDefault()
 */
CX_EXTERN CX_NONNULL
void cxPropertiesInit(CxProperties *prop, CxPropertiesConfig config);

/**
 * Destroys the properties interface.
 *
 * @note Even when you are certain that you did not use the interface in a
 * way that caused a memory allocation, you should call this function anyway.
 * Future versions of the library might add features that need additional memory,
 * and you really don't want to search the entire code where you might need to
 * add a call to this function.
 *
 * @param prop the properties interface
 */
CX_EXTERN CX_NONNULL
void cxPropertiesDestroy(CxProperties *prop);

/**
 * Destroys and re-initializes the properties interface.
 *
 * You might want to use this to reset the parser after
 * encountering a syntax error.
 *
 * @param prop the properties interface
 */
CX_EXTERN CX_NONNULL
void cxPropertiesReset(CxProperties *prop);

/**
 * Initialize a properties parser with the default configuration.
 *
 * @param prop (@c CxProperties*) the properties interface
 * @see cxPropertiesInit()
 */
#define cxPropertiesInitDefault(prop) \
        cxPropertiesInit(prop, cx_properties_config_default)

/**
 * Fills the input buffer with data.
 *
 * After calling this function, you can parse the data by calling
 * cxPropertiesNext().
 *
 * @remark The properties interface tries to avoid allocations.
 * When you use this function and cxPropertiesNext() interleaving,
 * no allocations are performed. However, you must not free the
 * pointer to the data in that case. When you invoke the fill
 * function more than once before calling cxPropertiesNext(),
 * the additional data is appended - inevitably leading to
 * an allocation of a new buffer and copying the previous contents.
 *
 * @param prop the properties interface
 * @param buf a pointer to the data
 * @param len the length of the data
 * @retval zero success
 * @retval non-zero a memory allocation was necessary but failed
 * @see cxPropertiesFill()
 */
CX_EXTERN CX_NONNULL CX_ACCESS_R(2, 3)
int cxPropertiesFilln(CxProperties *prop, const char *buf, size_t len);

/**
 * Internal function, do not use.
 *
 * @param prop the properties interface
 * @param str the text to fill in
 * @retval zero success
 * @retval non-zero a memory allocation was necessary but failed
 */
CX_NONNULL CX_INLINE
int cx_properties_fill(CxProperties *prop, cxstring str) {
    return cxPropertiesFilln(prop, str.ptr, str.length);
}

/**
 * Fills the input buffer with data.
 *
 * After calling this function, you can parse the data by calling
 * cxPropertiesNext().
 *
 * @attention The properties interface tries to avoid allocations.
 * When you use this function and cxPropertiesNext() interleaving,
 * no allocations are performed. However, you must not free the
 * pointer to the data in that case. When you invoke the fill
 * function more than once before calling cxPropertiesNext(),
 * the additional data is appended - inevitably leading to
 * an allocation of a new buffer and copying the previous contents.
 *
 * @param prop the properties interface
 * @param str the text to fill in
 * @retval zero success
 * @retval non-zero a memory allocation was necessary but failed
 * @see cxPropertiesFilln()
 */
#define cxPropertiesFill(prop, str) cx_properties_fill(prop, cx_strcast(str))

/**
 * Specifies stack memory that shall be used as an internal buffer.
 *
 * @param prop the properties interface
 * @param buf a pointer to stack memory
 * @param capacity the capacity of the stack memory
 */
CX_EXTERN CX_NONNULL
void cxPropertiesUseStack(CxProperties *prop, char *buf, size_t capacity);

/**
 * Retrieves the next key/value-pair.
 *
 * This function returns zero as long as there are key/value-pairs found.
 * If no more key/value-pairs are found, #CX_PROPERTIES_NO_DATA is returned.
 *
 * When an incomplete line is encountered, #CX_PROPERTIES_INCOMPLETE_DATA is
 * returned, and you can add more data with #cxPropertiesFill().
 *
 * @remark The incomplete line will be stored in an internal buffer, which is
 * allocated on the heap, by default. If you want to avoid allocations,
 * you can specify sufficient space with cxPropertiesUseStack() after
 * initialization with cxPropertiesInit().
 *
 * @attention The returned strings will point into a buffer that might not be
 * available later. It is strongly recommended to copy the strings for further
 * use.
 *
 * @param prop the properties interface
 * @param key a pointer to the cxstring that shall contain the property name
 * @param value a pointer to the cxstring that shall contain the property value
 * @retval CX_PROPERTIES_NO_ERROR (zero) a key/value pair was found
 * @retval CX_PROPERTIES_NO_DATA there is no (more) data in the input buffer
 * @retval CX_PROPERTIES_INCOMPLETE_DATA the data in the input buffer is incomplete
 * (fill more data and try again)
 * @retval CX_PROPERTIES_NULL_INPUT the input buffer was never filled
 * @retval CX_PROPERTIES_INVALID_EMPTY_KEY the properties data contains an illegal empty key
 * @retval CX_PROPERTIES_INVALID_MISSING_DELIMITER the properties data contains a line without delimiter
 * @retval CX_PROPERTIES_BUFFER_ALLOC_FAILED an internal allocation was necessary but failed
 */
CX_EXTERN CX_NONNULL CX_NODISCARD
CxPropertiesStatus cxPropertiesNext(CxProperties *prop, cxstring *key, cxstring *value);

/**
 * The size of the stack memory that `cxPropertiesLoad()` will reserve with `cxPropertiesUseStack()`.
 */
CX_EXPORT extern const unsigned cx_properties_load_buf_size;

/**
 * The size of the stack memory that `cxPropertiesLoad()` will use to read contents from the file.
 */
CX_EXPORT extern const unsigned cx_properties_load_fill_size;

/**
 * Internal function - use cxPropertiesLoad() instead.
 *
 * @param allocator the allocator for the values
 * @param filename the file name
 * @param target the target map
 * @param config the parser config
 * @return status code
 */
CX_EXTERN CX_NONNULL_ARG(3)
CxPropertiesStatus cx_properties_load(const CxAllocator *allocator,
        cxstring filename, CxMap *target, CxPropertiesConfig config);

/**
 * Loads properties from a file and inserts them into a map.
 *
 * Entries are added to the map, possibly overwriting existing entries.
 *
 * The map must either store pointers of type @c char*, or elements of type cxmutstr.
 * Any other configuration is not supported.
 *
 * @note When the parser finds an error, all successfully parsed keys before the error
 * are added to the map nonetheless.
 *
 * @param allocator the allocator for the values that will be stored in the map
 * @param filename (any string) the absolute or relative path to the file
 * @param target (@c CxMap*) the map where the properties shall be added
 * @param config the parser config
 * @retval CX_PROPERTIES_NO_ERROR (zero) at least one key/value pair was found
 * @retval CX_PROPERTIES_NO_DATA the file is syntactically OK, but does not contain properties
 * @retval CX_PROPERTIES_INCOMPLETE_DATA unexpected end of file
 * @retval CX_PROPERTIES_INVALID_EMPTY_KEY the properties data contains an illegal empty key
 * @retval CX_PROPERTIES_INVALID_MISSING_DELIMITER the properties data contains a line without delimiter
 * @retval CX_PROPERTIES_BUFFER_ALLOC_FAILED an internal allocation was necessary but failed
 * @retval CX_PROPERTIES_FILE_ERROR a file operation failed; depending on the system @c errno might be set
 * @retval CX_PROPERTIES_MAP_ERROR storing a key/value pair in the map failed
 * @see cxPropertiesLoadDefault()
 */
#define cxPropertiesLoad(allocator, filename, target, config) \
    cx_properties_load(allocator, cx_strcast(filename), target, config)

/**
 * Loads properties from a file and inserts them into a map with a default config.
 *
 * Entries are added to the map, possibly overwriting existing entries.
 *
 * The map must either store pointers of type @c char*, or elements of type cxmutstr.
 * Any other configuration is not supported.
 *
 * @note When the parser finds an error, all successfully parsed keys before the error
 * are added to the map nonetheless.
 *
 * @param allocator the allocator for the values that will be stored in the map
 * @param filename (any string) the absolute or relative path to the file
 * @param target (@c CxMap*) the map where the properties shall be added
 * @retval CX_PROPERTIES_NO_ERROR (zero) at least one key/value pair was found
 * @retval CX_PROPERTIES_NO_DATA the file is syntactically OK, but does not contain properties
 * @retval CX_PROPERTIES_INCOMPLETE_DATA unexpected end of file
 * @retval CX_PROPERTIES_INVALID_EMPTY_KEY the properties data contains an illegal empty key
 * @retval CX_PROPERTIES_INVALID_MISSING_DELIMITER the properties data contains a line without delimiter
 * @retval CX_PROPERTIES_BUFFER_ALLOC_FAILED an internal allocation was necessary but failed
 * @retval CX_PROPERTIES_FILE_ERROR a file operation failed; depending on the system @c errno might be set
 * @retval CX_PROPERTIES_MAP_ERROR storing a key/value pair in the map failed
 * @see cxPropertiesLoad()
 */
#define cxPropertiesLoadDefault(allocator, filename, target) \
    cx_properties_load(allocator, cx_strcast(filename), target, cx_properties_config_default)

#endif // UCX_PROPERTIES_H