diff options
| -rw-r--r-- | 1-24_syntax-checker.c | 232 |
1 files changed, 122 insertions, 110 deletions
diff --git a/1-24_syntax-checker.c b/1-24_syntax-checker.c index f56e4f7..239999f 100644 --- a/1-24_syntax-checker.c +++ b/1-24_syntax-checker.c @@ -15,135 +15,147 @@ * * I can tackle this one the same way I tackled the previous exercise: with a * FSM. The trick is in catching the mismatched levels. + * + * Post-solution note: switch() would've made this MUCH shorter... */ -/* Create our nestable counts. These keep track of each type of syntax - * character. */ -#define PARENS 0 -#define BRACKETS 1 -#define BRACES 2 - -/* Create our states, which tell the parser what's going on. INSQ, INDQ, and - * INCM are much larger so it's easier to tell what's what. If I were better - * versed in binary operations, this could use less RAM. I intend to revisit - * this later on. */ -#define OUT 0 -#define INPR 1 -#define INBK 2 -#define INBC 3 -#define INSQ 100 -#define INDQ 1000 -#define INCM 10000 - char c; -int counts[3]; -int state, i, linenr; -int main() { - for (i = 0; i < 3; ++i) { - counts[i] = 0; - } +/* Set the state/count variables */ +int linenr, parens, brackets, braces, singqs, dubqs, escapes, mcomms, scomms = 0; - state = OUT; +int main() { linenr = 1; // Begin streaming! while ((c = getchar()) != EOF) { - if (c == '\n') { - linenr += 1; - if (state >= INSQ) { - break; + if (scomms == 1) { + if (c == '\n') { + scomms--; + } else { + continue; } - } - if (c == '(') { - counts[PARENS] += 1; - state += INPR; - } - if (c == ')') { - counts[PARENS] -= 1; - state -= INPR; - if (counts[PARENS] < 0) { - break; + } else if (mcomms == 1) { + if (c == '*') { + if (getchar() == '/') { + mcomms--; + } } - } - if (c == '[') { - counts[BRACKETS] += 1; - state += INBK; - } - if (c == ']') { - counts[BRACKETS] -= 1; - state -= INBK; - if (counts[BRACKETS] < 0) { - break; + } else { + // Check for escape sequences + if (c == '\\') { + escapes++; + c = getchar(); + // This does not detect all sequences; just the ones covered in Chapter 1. + if (c != '\\' || c != 't' || c != '\'' || c != '"' || c != 'n' || c != 'b' || c != '0') { + break; + } else { + escapes--; + } } - } - if (c == '{') { - counts[BRACES] += 1; - state += INBC; - } - if (c == '}') { - counts[BRACES] -= 1; - state -= INBC; - if (counts[BRACES] < 0) { - break; + // Newline behavior + if (c == '\n') { + if (singqs > 0 || dubqs > 0) { + break; + } + linenr += 1; } - } - if (c == '"' && state > INDQ) { - state -= INDQ; - if (state < 0) { - break; + // Parentheses + if (c == '(') { + parens += 1; } - } - if (c == '"' && state < INSQ) { - state += INDQ; - if (state >= (INDQ * 2)) { - break; + if (c == ')') { + parens -= 1; + if (parens < 0) { + break; + } } - } - if (c == '\'' && state > INSQ && state < INDQ) { - state -= INSQ; - if (state < 0) { - break; + // Brackets + if (c == '[') { + brackets += 1; } - } - if (c == '\'' && state < INSQ) { - state += INSQ; - if (state >= (INSQ * 2)) { - break; + if (c == ']') { + brackets--; + if (brackets < 0) { + break; + } + } + // Braces + if (c == '{') { + braces++; + } + if (c == '}') { + braces--; + if (braces < 0) { + break; + } + } + // Double quotes + if (c == '"') { + if (dubqs == 0) { + dubqs++; + } else { + dubqs--; + } + } + // Single quotes, which are only checked outside of doubles. + if (c == '\'' && dubqs == 0) { + if (singqs == 0) { + singqs++; + } else { + singqs--; + } + } + // Comment detection + if (c == '/') { + if (getchar() == '*') { + mcomms++; + } + if (getchar() == '/') { + scomms++; + } } } } - if (state != 0) { - printf("SYNTAX ERROR: "); - - if (state >= INSQ && state < INDQ) { - printf("Unclosed single quote on line %d!\n", linenr); - return 1; - } - if (counts[PARENS] > 0) { - printf("Unclosed parenthesis on line %d!\n", linenr); - return 1; - } - if (counts[PARENS] < 0) { - printf("Too many close parentheses on line %d!\n", linenr); - return 1; - } - if (counts[BRACKETS] > 0) { - printf("Unclosed brackets on line %d!\n", linenr); - return 1; - } - if (counts[BRACKETS] < 0) { - printf("Too many close brackets on line %d!\n", linenr); - return 1; - } - if (counts[BRACES] > 0) { - printf("Unclosed braces on line %d!\n", linenr); - return 1; - } - if (counts[BRACES] < 0) { - printf("Too many close braces on line %d!\n", linenr); - return 1; - } + if (escapes > 0) { + printf("Invalid escape sequence on line %d!\n", linenr); + return 1; + } + if (singqs > 0) { + printf("Unclosed single quote on line %d!\n", linenr); + return 1; + } + if (dubqs > 0) { + printf("Unclosed double quote on line %d!\n", linenr); + return 1; + } + if (brackets > 0) { + printf("Unclosed brackets on line %d!\n", linenr); + return 1; + } + if (brackets < 0) { + printf("Too many close brackets on line %d!\n", linenr); + return 1; + } + if (parens > 0) { + printf("Unclosed parenthesis on line %d!\n", linenr); + return 1; + } + if (parens < 0) { + printf("Too many close parentheses on line %d!\n", linenr); + return 1; + } + if (braces > 0) { + printf("Unclosed braces on line %d!\n", linenr); + return 1; + } + if (braces < 0) { + printf("Too many close braces on line %d!\n", linenr); + return 1; + } + if (mcomms == 1) { + printf("Unclosed comment at end of file!\n"); + return 1; } printf("All clean.\n"); |