From e859c083a97edf6be14b17c652835f1e27b75210 Mon Sep 17 00:00:00 2001 From: zlg Date: Fri, 20 Feb 2015 22:35:43 -0800 Subject: Solve Exercise 5-20: Expanded `dcl` This marks the end of chapter 5. Admittedly, the solution for 5-20 is terrible, but it does what it's supposed to do. I'm just excited to move onto chapter 6 and start learning structures! --- ch5/5-20_expanded-dcl.c | 215 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 215 insertions(+) create mode 100644 ch5/5-20_expanded-dcl.c diff --git a/ch5/5-20_expanded-dcl.c b/ch5/5-20_expanded-dcl.c new file mode 100644 index 0000000..d7d4c5c --- /dev/null +++ b/ch5/5-20_expanded-dcl.c @@ -0,0 +1,215 @@ +#include +#include +#include + +/* The C Programming Language: 2nd Edition + * + * Exercise 5-20: Expand `dcl` to handle declarations with function + * argument types, qualifiers like `const`, and so on. + * + * Notes: Basically, you need a qualifier string and an accepting + * type string. This solution is nowhere near robust, and is in great + * need of a refactor, but honestly I don't know where to begin fixing + * this mess. + * + * The robust way to do this would be to have a list of valid tokens, their + * semantic meaning, and a sort of "test string" that could be verified for + * integrity before attempting to output. Once it's been checked for sanity, + * the gathered details should be added to the final sentence in grammatical + * order. That requires more work than this exercise is worth, however. If I + * find myself bored with C, I'll come back to this, as it could be done much + * better than what's here. Patches welcome! + */ + +#define MAXTOKEN 100 +#define BUFSIZE 100 + +enum { NAME, PARENS, BRACKETS, TYPE, QUAL }; + +void dcl(void); +void dirdcl(void); +int gettoken(void); +char buf[BUFSIZE]; +int bufp = 0; +int tokentype; +int accept = 0; + +char qual[MAXTOKEN]; +char token[MAXTOKEN]; +char name[MAXTOKEN]; +char datatype[MAXTOKEN]; +char clause[MAXTOKEN]; +char out[1000]; +int get_line(char *s, int lim); + +void dcl(void) { + int ns; + for (ns = 0; gettoken() == '*'; ns++) { + } + dirdcl(); + while (ns-- > 0) { + strcat(out, " pointer to"); + } +} + +void dirdcl(void) { + int type; + if (tokentype == '(') { + dcl(); + if (tokentype != ')') { + printf("error: missing )\n"); + } + } else if (tokentype == QUAL) { + strcat(qual, token); + gettoken(); + } else if (tokentype == TYPE) { + strcat(datatype, " "); + strcat(datatype, token); + } else if (tokentype == NAME) { + strcpy(name, token); + } else { + printf("error: expected name or (dcl)\n"); + } + while ((type = gettoken()) == PARENS || type == BRACKETS) { + if (type == PARENS) { + strcat(out, " function returning"); + if (accept == 1) { + strcpy(clause, " accepting "); + while ((type = gettoken()) != '\n' && type != ')') { + if (type == '(') { + continue; + } + if (type == QUAL) { + strcat(clause, token); + strcat(clause, " "); + continue; + } else if (type == TYPE) { + strcat(clause, token); + return; + } else { + printf("Error: invalid argument type: %s\n", token); + } + } + strcat(clause, "void"); + return; + } + } else { + strcat(out, " array"); + strcat(out, token); + strcat(out, " of"); + } + } +} + +int gettoken(void) { + char *p = token; + while (buf[bufp] == ' ' || buf[bufp] == '\t') { + bufp++; + } + if (buf[bufp] == '/') { + if (buf[bufp+1] == '/' || buf[bufp+1] == '*') { + while (buf[bufp] != '\n') { + bufp++; + } + } + return tokentype = buf[bufp]; + } else if (buf[bufp] == '(') { + if (buf[++bufp] == ')') { + strcpy(token, "()"); + bufp++; + accept = 1; + return tokentype = PARENS; + } else { + return tokentype = '('; + } + } else if (buf[bufp] == '[') { + while (buf[bufp] != ']') { + if (buf[bufp + 1] == '[') { + return tokentype = buf[bufp + 1]; + } + if (isspace(buf[bufp])) { + bufp++; + continue; + } + *p++ = buf[bufp++]; + } + *p++ = buf[bufp++]; + *p = '\0'; + return tokentype = BRACKETS; + } else if (isalpha(buf[bufp])) { + *p++ = buf[bufp++]; + while (isalnum(buf[bufp])) { + *p++ = buf[bufp++]; + } + *p = '\0'; + /* check types */ + if (strcmp(token, "const") == 0 || + strcmp(token, "static") == 0 || + strcmp(token, "long") == 0 || + strcmp(token, "short") == 0) { + return tokentype = QUAL; + } + if (strcmp(token, "int") == 0 || + strcmp(token, "double") == 0 || + strcmp(token, "unsigned") == 0 || + strcmp(token, "signed") == 0 || + strcmp(token, "void") == 0 || + strcmp(token, "char") == 0) { + return tokentype = TYPE; + } + return tokentype = NAME; + } else { + return tokentype = buf[bufp++]; + } +} + +/* Returns length of line including \n + */ +int get_line(char *s, int lim) { + int c, i; + for (i = 0; i < lim - 1 && (c=getchar()) != EOF && c != '\n'; ++i) { + *s++ = c; + } + if (c == '\n') { + *s++ = c; + i++; + } + *s = '\0'; + return i; +} + +int main(void) { + int len = 0; + while ((len = get_line(buf, BUFSIZE)) > 0 && buf[len - 1] != EOF) { + if (len == 1 && buf[bufp] == '\n') { + continue; + } + bufp = 0; + datatype[0] = 0; + qual[0] = 0; + gettoken(); + if (tokentype == QUAL) { + strcpy(qual, token); + gettoken(); + } + if (tokentype == TYPE) { + strcpy(datatype, token); + } + out[0] = '\0'; + name[0] = '\0'; + dcl(); + if (tokentype == ')') { + printf("error: too many closing parens\n\n"); + } else if (tokentype == ']') { + printf("error: too many closing brackets\n\n"); + } else if (tokentype == '(') { + printf("error: too many opening parens\n\n"); + } else if (tokentype == '[') { + printf("error: too many opening brackets\n\n"); + } else { + printf("%s: %s %s %s %s\n\n", name, out, qual, datatype, clause); + } + accept = 0; + } + return 0; +} -- cgit v1.2.3-70-g09d2 /tr> Also tweaked the export command to report correctly. 2018-10-10cli: Add "export" commandzlg2-5/+54 The export command is like the import command; currently supporting YAML output, but ready to be expanded as needed. 2018-10-10cli: Add "import" commandzlg5-1/+76 Currently the import command will only accept YAML files, but is ready for expansion to other formats as needed. 2018-10-09Bump to 0.3alpha6 for PyPIzlg1-1/+1 2018-10-09cli: Add "notes" commandzlg2-4/+74 The "notes" command will show the user what their notes for a particular game are. The output can be piped anywhere the user wants, such as a pager or a file. If "notes" is passed with the "--edit" or "-e" flag, vgstash will open a temporary file with the game's notes already inside and edit it using the program pointed to by the EDITOR environment variable. When the editor is closed (with a successful exit status), vgstash updates the game's notes and exits. The defaults for the testing environment ("cat" for non-interactive, "vim" for interactive) may need tweaking on other operating systems. Patches for these platforms are very welcome. 2018-10-09update_game: ensure notes are also savedzlg1-2/+2 2018-10-09cli: add 'update' commandzlg3-20/+92 Two helper functions were also added to the vgstash package to ease client workflows. This commit marks the final core function necessary to manipulate a vgstash DB on the command line. 2018-10-06cli: Add "delete" commandzlg2-0/+19 Unlike the old version of vgstash, the new one does not accept row IDs as arguments for removal. Instead, it accepts two mandatory arguments: the title of the game, and the system it's on. This is in line with the database itself, using the title and system as primary keys. 2018-10-06Remove ID field from DBzlg3-38/+46 The sqlite database already uses a game's title and system as the primary keys. Row IDs are redundant. 2018-10-06cli: change "Status" heading to "Progress"zlg2-36/+40 2018-09-29Bump to 0.3alpha5 for PyPIzlg1-1/+1 2018-09-29cli: Add pretty printing to 'list' commandzlg3-17/+107 Also add the "--width" option to specify the maximum width of the table. 2018-09-08setup.py: Bump to alpha4 for PyPIzlg1-1/+1 2018-09-08cli: add '--raw' option to list commandzlg2-9/+45 Add '--raw' option to the list command, in addition to proper note expansion. Newline characters in notes are escaped to be friendly to scripting. This option may be shortened to '-r' at the user's convenience. In raw output mode, the information is formatted in plain pipe-delimited strings, one line per row: title|system|ownership|progress|notes ownership and progress are printed in their numeric form, consistent with the OWNERSHIP and PROGRESS dictionaries in the vgstash package. An empty notes field will result in a line ending with a pipe and no whitespace following it. 2018-09-08Add remaining filters to vgstash packagezlg1-2/+11 2018-09-04Update LICENSE to match setup.pyzlg1-80/+67 Whoops. 2018-09-03Branch off from master with pytest, tox, clickzlg16-778/+779 This commit is huge, but contains everything needed for a "proper" build system built on pytest + tox and a CLI built with click. For now, this branch will contain all new vgstash development activity until it reaches feature parity with master. The CLI is installed to pip's PATH. Only the 'init', 'add', and 'list' commands work, with only two filters. This is pre-alpha software, and is therefore not stable yet. 2018-03-18Flesh out filter types and ownership statuszlg3-82/+144 It's time for a refactor to a module; the functionality and interface are clashing. 2018-03-18README.mdown: break line correctlyzlg1-1/+1 2018-03-18add 'playlog' list filterzlg2-2/+9 This filter is used to get an idea of which games you're currently playing through, so you can prioritize games to play when you're bored and detect it when you've beaten a game but haven't marked it as such. 2018-03-13Update helpers a bitzlg1-2/+9 At present, user modification is needed to make these seamless. vgup() may need to be axed in favor of telling the user to make an alias. 2018-03-13Make VGSTASH_DB_LOCATION point to a filezlg2-21/+20 It used to point to a directory, which would then look for .vgstash.db. This behavior was kind of backwards and I don't remember why I did it that way. This change gives users more control over where they put their DB. Be sure to update your environment variable if you have it set! 2016-11-18Remove settings from helpers.shZe Libertine Gamer1-5/+0 Sourcing them in .bash_profile screws up login if they're set. 2016-11-15Correct phrasing in README.Ze Libertine Gamer1-4/+4 2016-11-13DerpZe Libertine Gamer1-0/+1 2016-11-03Improve error handling in shell scriptsZe Libertine Gamer4-3/+23 2016-10-24Correct run_again, add recursionZe Libertine Gamer1-0/+4 Loops and functions -- oh my, what a useful combination. :) 2016-10-21Add quotes to correct behavior for arglistZe Libertine Gamer1-1/+1 2016-10-14updater.sh: add recursion, error handlingZe Libertine Gamer1-43/+101 2016-10-14Correct pipe-handling behaviorZe Libertine Gamer1-1/+9 2016-10-12Clarify a method to move between platformsZe Libertine Gamer1-2/+5 Also correct a typo.