telodendria/src/Config.c

#include <Config.h>

#include <stdlib.h>
#include <ctype.h>
#include <string.h>

#ifndef CONFIG_BUFFER_BLOCK
#define CONFIG_BUFFER_BLOCK 32
#endif

struct ConfigDirective {
    Array *values;
    HashMap *children;
};

struct ConfigParseResult {
    unsigned int ok : 1;
    union {
        size_t lineNumber;
        HashMap *confMap;
    } data;
};

typedef enum ConfigToken {
    TOKEN_UNKNOWN,
    TOKEN_NAME,
    TOKEN_MACRO_ASSIGNMENT,
    TOKEN_VALUE,
    TOKEN_SEMICOLON,
    TOKEN_BLOCK_OPEN,
    TOKEN_BLOCK_CLOSE,
    TOKEN_MACRO,
    TOKEN_EOF
} ConfigToken;

typedef struct ConfigParserState {
    FILE           *stream;
    unsigned int 	line;

    char           *token;
    size_t 		tokenSize;
    size_t 		tokenLen;
    ConfigToken tokenType;

    HashMap *macroMap;

} ConfigParserState;

unsigned int
ConfigParseResultOk(ConfigParseResult *result)
{
    return result ? result->ok : 0;
}

size_t
ConfigParseResultLineNumber(ConfigParseResult *result)
{
    return result && !result->ok ? result->data.lineNumber : 0;
}

HashMap *
ConfigParseResultGet(ConfigParseResult *result)
{
    return result && result->ok ? result->data.confMap : NULL;
}

void
ConfigParseResultFree(ConfigParseResult *result)
{
    /*
     * Note that if the parse was valid, the hash map
     * needs to be freed separately.
     */
    free(result);
}

Array *
ConfigValuesGet(ConfigDirective *directive)
{
    return directive ? directive->values : NULL;
}

HashMap *
ConfigChildrenGet(ConfigDirective *directive)
{
    return directive ? directive->children : NULL;
}

/*
 * Takes a void pointer because it is only used with
 * HashMapIterate(), which requires a pointer to a function
 * that takes a void pointer.
 */
static void
ConfigDirectiveFree(void *ptr)
{
    ConfigDirective *directive = ptr;
    size_t i;

    if (!directive)
    {
        return;
    }

    for (i = 0; i < ArraySize(directive->values); i++)
    {
        free(ArrayGet(directive->values, i));
    }

    ArrayFree(directive->values);
    ConfigFree(directive->children);

    free(directive);
}

void
ConfigFree(HashMap *conf)
{
    HashMapIterate(conf, ConfigDirectiveFree);
    HashMapFree(conf);
}

static ConfigParserState *
ConfigParserStateCreate(FILE * stream)
{
    ConfigParserState *state = malloc(sizeof(ConfigParserState));
    if (!state)
    {
        return NULL;
    }

    state->macroMap = HashMapCreate();

    if (!state->macroMap)
    {
        free(state);
        return NULL;
    }

    state->stream = stream;
    state->line = 1;
    state->token = NULL;
    state->tokenSize = 0;
    state->tokenLen = 0;
    state->tokenType = TOKEN_UNKNOWN;

    return state;
}

static void
ConfigParserStateFree(ConfigParserState *state)
{
    if (!state)
    {
        return;
    }

    free(state->token);

    HashMapIterate(state->macroMap, free);
    HashMapFree(state->macroMap);

    free(state);
}

static int
ConfigIsNameChar(int c)
{
    return isdigit(c) || isalpha(c) || (c == '-' || c == '_');
}

static char
ConfigConsumeWhitespace(ConfigParserState *state)
{
    int c;
    while (isspace(c = fgetc(state->stream)))
    {
        if (c == '\n')
        {
            state->line++;
        }
    }
    return c;
}

static void
ConfigConsumeLine(ConfigParserState *state)
{
    while (fgetc(state->stream) != '\n');
    state->line++;
}

static void
ConfigTokenSeek(ConfigParserState *state)
{
    int c;

    /* If we already hit EOF, don't do anything */
    if (state->tokenType == TOKEN_EOF) {
        return;
    }
    while ((c = ConfigConsumeWhitespace(state)) == '#') {
        ConfigConsumeLine(state);
    }

    /*
     * After all whitespace and comments are consumed, identify the
     * token by looking at the next character
     */

    if (feof(state->stream)) {
        state->tokenType = TOKEN_EOF;
        return;
    }
    if (ConfigIsNameChar(c)) {
        state->tokenLen = 0;

        /* Read the key/macro into state->token */
        if (!state->token) {
            state->tokenSize = CONFIG_BUFFER_BLOCK;
            state->token = malloc(CONFIG_BUFFER_BLOCK);
        }
        state->token[state->tokenLen] = c;
        state->tokenLen++;

        while (ConfigIsNameChar((c = fgetc(state->stream)))) {
            state->token[state->tokenLen] = c;
            state->tokenLen++;

            if (state->tokenLen >= state->tokenSize) {
                state->tokenSize += CONFIG_BUFFER_BLOCK;
                state->token = realloc(state->token,
                                        state->tokenSize);
            }
        }

        state->token[state->tokenLen] = '\0';
        state->tokenLen++;

        if (!isspace(c)) {
            state->tokenType = TOKEN_UNKNOWN;
        } else {
            state->tokenType = TOKEN_NAME;

            if (c == '\n') {
                state->line++;
            }
        }

    } else {
        switch (c) {
            case '=':
                state->tokenType = TOKEN_MACRO_ASSIGNMENT;
                break;
            case '"':
                state->tokenLen = 0;
                state->tokenType = TOKEN_VALUE;

                /* read the value into state->curtok */
                while ((c = fgetc(state->stream)) != '"') {
                    if (c == '\n') {
                        state->line++;
                    }
                    /*
                     * End of the stream reached without finding
                     * a closing quote
                     */
                    if (feof(state->stream)) {
                        state->tokenType = TOKEN_EOF;
                        break;
                    }
                    state->token[state->tokenLen] = c;
                    state->tokenLen++;

                    if (state->tokenLen >= state->tokenSize) {
                        state->tokenSize += CONFIG_BUFFER_BLOCK;
                        state->token = realloc(state->token,
                                                state->tokenSize);
                    }
                }
                state->token[state->tokenLen] = '\0';
                state->tokenLen++;
                break;
            case ';':
                state->tokenType = TOKEN_SEMICOLON;
                break;
            case '{':
                state->tokenType = TOKEN_BLOCK_OPEN;
                break;
            case '}':
                state->tokenType = TOKEN_BLOCK_CLOSE;
                break;
            case '$':
                state->tokenLen = 0;
                /* read the macro name into state->curtok */
                while (ConfigIsNameChar(c = fgetc(state->stream))) {
                    state->token[state->tokenLen] = c;
                    state->tokenLen++;

                    if (state->tokenLen >= state->tokenSize) {
                        state->tokenSize += CONFIG_BUFFER_BLOCK;
                        state->token = realloc(state->token,
                                                state->tokenSize);
                    }
                }
                state->token[state->tokenLen] = '\0';
                state->tokenLen++;
                state->tokenType = TOKEN_MACRO;

                ungetc(c, state->stream);
                break;
            default:
                state->tokenType = TOKEN_UNKNOWN;
                break;
        }
    }

    /* Resize curtok to only use the bytes it needs */
    if (state->tokenLen) {
        state->tokenSize = state->tokenLen;
        state->token = realloc(state->token, state->tokenSize);
    }
}

static int
ConfigExpect(ConfigParserState *state, ConfigToken tokenType)
{
    return state->tokenType == tokenType;
}


static HashMap *
ConfigParseBlock(ConfigParserState *state, int level)
{
    HashMap *block = HashMapCreate();

    ConfigTokenSeek(state);

    while (ConfigExpect(state, TOKEN_NAME)) {
        char           *name = malloc(state->tokenLen + 1);
        strcpy(name, state->token);

        ConfigTokenSeek(state);
        if (ConfigExpect(state, TOKEN_VALUE) || ConfigExpect(state, TOKEN_MACRO)) {
            ConfigDirective *directive;

            directive = malloc(sizeof(ConfigDirective));
            directive->children = NULL;
            directive->values = ArrayCreate();

            while (ConfigExpect(state, TOKEN_VALUE) ||
                   ConfigExpect(state, TOKEN_MACRO)) {

                char *dval;
                char *dvalCpy;

                if (ConfigExpect(state, TOKEN_VALUE)) {
                    dval = state->token;
                } else if (ConfigExpect(state, TOKEN_MACRO)) {
                    dval = HashMapGet(state->macroMap, state->token);
                    if (!dval) {
                        goto error;
                    }
                } else {
                    dval = NULL;	/* Should never happen */
                }

                /* dval is a pointer which is overwritten with the next token. */
                dvalCpy = malloc(strlen(dval) + 1);
                strcpy(dvalCpy, dval);

                ArrayAdd(directive->values, dvalCpy);
                ConfigTokenSeek(state);
            }

            if (ConfigExpect(state, TOKEN_BLOCK_OPEN)) {
                /* token_seek(state); */
                directive->children = ConfigParseBlock(state, level + 1);
                if (!directive->children) {
                    goto error;
                }
            }

            /*
             * Append this directive to the current block,
             * overwriting a directive at this level with the same name.
             *
             * Note that if a value already exists with this name, it is
             * returned by HashMapSet() and then immediately passed to
             * ConfigDirectiveFree(). If the value does not exist, then
             * NULL is sent to ConfigDirectiveFree(), making it a no-op.
             */
            ConfigDirectiveFree(HashMapSet(block, name, directive));

        } else if (ConfigExpect(state, TOKEN_MACRO_ASSIGNMENT)) {
            ConfigTokenSeek(state);
            if (ConfigExpect(state, TOKEN_VALUE)) {
                char * valueCopy = malloc(strlen(state->token) + 1);
                strcpy(valueCopy, state->token);
                free(HashMapSet(state->macroMap, name, state->token));
                ConfigTokenSeek(state);
            } else {
                goto error;
            }
        } else {
            goto error;
        }

        if (!ConfigExpect(state, TOKEN_SEMICOLON)) {
            goto error;
        }
        ConfigTokenSeek(state);
    }

    if (ConfigExpect(state, level ? TOKEN_BLOCK_CLOSE : TOKEN_EOF)) {
        ConfigTokenSeek(state);
        return block;
    } else {
        goto error;
    }

    error:
    /* Only free the very top level, because this will recurse */
    if (!level) {
        ConfigFree(block);
    }
    return NULL;
}

ConfigParseResult *
ConfigParse(FILE * stream)
{
    ConfigParseResult *result;
    HashMap *conf;
    ConfigParserState *state;

    result = malloc(sizeof(ConfigParseResult));
    state = ConfigParserStateCreate(stream);
    conf = ConfigParseBlock(state, 0);

    if (!conf) {
        result->ok = 0;
        result->data.lineNumber = state->line;
    } else {
        result->ok = 1;
        result->data.confMap = conf;
    }

    ConfigParserStateFree(state);
    return result;
}