scl/src/lexer.c

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>

#include "include/lexer.h"
#include "include/dstr.h"
#include "include/token.h"
#include "include/util.h"

Lexer* thelexer = NULL;

void lexer_init(char* src) {
    thelexer = malloc(sizeof(Lexer));

    thelexer->src = src;
    thelexer->srcln = strlen(src);
    thelexer->cchar = thelexer->src;

    thelexer->tokens = calloc(TOKENS_MAX, sizeof(Token*));
    thelexer->ntokens = 0;
    thelexer->state = LEXER_STATE_CONFUSED;

    log_dbgf("created thelexer @ %p", thelexer);
}

void lexer_destroy(Lexer* lexer) {
    // Does not free lexer->src.
    for (int i = 0; i < lexer->ntokens; i++) token_destroy(lexer->tokens[i]);
}

void lexer_lex(Lexer* lexer) {
    while (*lexer->cchar) {
        switch (lexer->state) {
        case LEXER_STATE_CONFUSED: lexer_do_confused(lexer); break;
        case LEXER_STATE_NUM:      lexer_do_number(lexer); break;
        case LEXER_STATE_CALL:     lexer_do_call(lexer); break;
        default:                   break;
        }
    }
}

void lexer_do_confused(Lexer* lexer) {
    log_dbgf("lexer @ %p entered confused mode @ char '%c' (%d)", lexer,
             *lexer->cchar, (int)*lexer->cchar);

    if (isspace(*lexer->cchar)) lexer_inc(lexer);

    if (isdigit(*lexer->cchar)) {
        lexer->state = LEXER_STATE_NUM;
        lexer_do_number(lexer);
    } else {
        lexer->state = LEXER_STATE_CALL;
        lexer_do_call(lexer);
    }
}

void lexer_do_number(Lexer* lexer) {
    log_dbgf("lexer @ %p entered number mode @ char '%c' (%d)", lexer,
             *lexer->cchar, (int)*lexer->cchar);

    // Length of the number string.
    size_t numln;

    // Where the number string starts.
    char* start = lexer->cchar;

    for (numln = 0; *lexer->cchar && isdigit(*lexer->cchar); numln++)
        lexer_inc(lexer);

    char* num = malloc(numln + 1);
    memcpy(num, start, numln);
    num[numln] = '\0';

    lexer_add_token(lexer, token_init(TOKEN_TYPE_NUMBER, num, numln));
    lexer->state = LEXER_STATE_CONFUSED;
}

void lexer_do_call(Lexer* lexer) {
    log_dbgf("lexer @ %p entered call mode @ char '%c' (%d)", lexer,
             *lexer->cchar, (int)*lexer->cchar);

    // Size of the call string.
    size_t callln;

    // Where the call string starts.
    char* start = lexer->cchar;

    for (callln = 0;
         *lexer->cchar && (!isdigit(*lexer->cchar) && !isspace(*lexer->cchar));
         callln++)
        lexer_inc(lexer);

    char* call = malloc(callln + 1);
    memcpy(call, start, callln);
    call[callln] = '\0';

    lexer_add_token(lexer, token_init(TOKEN_TYPE_CALL, call, callln));

    lexer->state = LEXER_STATE_CONFUSED;
}

void lexer_inc(Lexer* lexer) {
    lexer->cchar += sizeof(char);
}

void lexer_add_token(Lexer* lexer, Token* token) {
    assert(lexer->ntokens < TOKENS_MAX);

    if (lexer->ntokens < TOKENS_MAX - 1) {
        lexer->tokens[lexer->ntokens] = token;
        lexer->ntokens++;

        log_dbgf("added token (total: %ld)", lexer->ntokens);
    }
}

void lexer_print(Lexer* lexer) { lexer_print_i(lexer, 0); }

void lexer_print_i(Lexer* lexer, int ilvl) {
    INDENT_BEGIN(ilvl);
    INDENT_TITLE("Lexer", lexer);
    INDENT_FIELD_NONL_START("state")
        lexerstate_print_raw(lexer->state);
    INDENT_FIELD_NONL_END
    INDENT_FIELD("srcln", "%ld", lexer->srcln);
    INDENT_FIELD_NL("src", "\"%s\"", lexer->src);
    INDENT_FIELD("cchar", "'%c'", *lexer->cchar);
    INDENT_FIELD("ntokens", "%ld", lexer->ntokens);
    INDENT_FIELD_LIST("tokens", lexer->tokens, lexer->ntokens, token_print_i);
#if 0
    printf("%s tokens: [\n", INDENT_spacing->buf);

    for (int i = 0; i < lexer->ntokens; i++) {
        token_print_i(lexer->tokens[i], ilvl + 2);
        printf(",\n\n");
    }
#endif
}

void lexerstate_print_raw(LexerState s) {
    if (s > LEXER_STATE_MAX) {
        printf("Unknown (%d)", s);
        log_dbgf("%d is not a valid LexerState (max: %d)", s, TOKEN_TYPE_MAX);
    } else printf("%s", lexerstate_names[s]);
}

#include "../build/grammars/grammar.tab.h"

int yylex(void) {
    if (*thelexer->cchar == '\0') return YYEOF;

    switch (*thelexer->cchar) {
        case ' ':
        case '\t':
            thelexer->cchar++;
    }

    // Assign & consume current character.
    int c = *thelexer->cchar++;

    switch (c) {
        case '+':
            return PLUS;
    }

    if (isdigit(c)) {
        int value = c - '0';  // Start with the first digit
        while (isdigit(*thelexer->cchar)) {
            value = value * 10 + (*thelexer->cchar - '0');  // Accumulate value
            thelexer++;
        }
        yylval.intval = value;  // Set the token value
        return NUM; // Return the INTEGER token type
    }

    fprintf(stderr, "Unexpected character: %c\n", c);

    return 0;
}