diff options
Diffstat (limited to 'examples')
| -rw-r--r-- | examples/c/README.md | 8 | ||||
| -rw-r--r-- | examples/c/bistromathic/README.md | 26 | ||||
| -rwxr-xr-x | examples/c/bistromathic/bistromathic.test | 41 | ||||
| -rw-r--r-- | examples/c/bistromathic/local.mk | 2 | ||||
| -rw-r--r-- | examples/c/bistromathic/parse.y | 213 |
5 files changed, 233 insertions, 57 deletions
diff --git a/examples/c/README.md b/examples/c/README.md index e69004c4..e1e04d84 100644 --- a/examples/c/README.md +++ b/examples/c/README.md @@ -50,9 +50,13 @@ This example is a straightforward conversion of the 'calc' example to the push-parser model. ## bistromathic - all the bells and whistles -This example demonstrates the best practices when using Bison. -- Its interface is pure. +This example demonstrates best practices when using Bison. - Its hand-written scanner tracks locations. +- Its interface is pure. +- Its interface is "incremental", well suited for interaction: it uses the + push-parser API to feed the parser with the incoming tokens. +- It features an interactive command line with completion based on the + parser state, based on `yyexpected_tokens`. - It uses a custom syntax error with location, lookahead correction and token internationalization. - It supports debug traces with semantic values. diff --git a/examples/c/bistromathic/README.md b/examples/c/bistromathic/README.md index 8bef5136..6b376b71 100644 --- a/examples/c/bistromathic/README.md +++ b/examples/c/bistromathic/README.md @@ -1,7 +1,11 @@ # bistromathic - all the bells and whistles -This example demonstrates the best practices when using Bison. -- Its interface is pure. +This example demonstrates best practices when using Bison. - Its hand-written scanner tracks locations. +- Its interface is pure. +- Its interface is "incremental", well suited for interaction: it uses the + push-parser API to feed the parser with the incoming tokens. +- It features an interactive command line with completion based on the + parser state, based on `yyexpected_tokens`. - It uses a custom syntax error with location, lookahead correction and token internationalization. - It supports debug traces with semantic values. @@ -17,16 +21,14 @@ Copyright (C) 2020 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. -This program is free software: you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation, either version 3 of the License, or -(at your option) any later version. +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with no +Invariant Sections, with no Front-Cover Texts, and with no Back-Cover +Texts. A copy of the license is included in the "GNU Free +Documentation License" file as part of this distribution. -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. +LocalWords: bistromathic yyexpected lookahead ispell american +LocalWords: MERCHANTABILITY -You should have received a copy of the GNU General Public License -along with this program. If not, see <http://www.gnu.org/licenses/>. ---> diff --git a/examples/c/bistromathic/bistromathic.test b/examples/c/bistromathic/bistromathic.test index 5ecff945..f42fb29d 100755 --- a/examples/c/bistromathic/bistromathic.test +++ b/examples/c/bistromathic/bistromathic.test @@ -18,47 +18,64 @@ cat >input <<EOF 1+2*3 EOF -run 0 7 +run 0 '> 1+2*3 +7 +> ' cat >input <<EOF (1+2) * 3 EOF -run 0 9 -run -noerr 0 9 -p +run 0 '> (1+2) * 3 +9 +> ' +run -noerr 0 '> (1+2) * 3 +9 +> ' -p cat >input <<EOF a = 256 sqrt (a) EOF -run 0 '256 -16' +run 0 '> a = 256 +256 +> sqrt (a) +16 +> ' cat >input <<EOF a = .16 b = 10 ^ 2 sqrt (a * b) EOF -run 0 '0.16 +run 0 '> a = .16 +0.16 +> b = 10 ^ 2 100 -4' +> sqrt (a * b) +4 +> ' cat >input <<EOF * EOF -run 0 'err: 1.1: syntax error: expected end of file or - or ( or end of line or double precision number or function or variable before *' +run 0 '> * +> err: 1.1: syntax error: expected end of file or - or ( or exit or double precision number or function or variable before *' cat >input <<EOF 1 + 2 * * 3 EOF -run 0 'err: 1.9: syntax error: expected - or ( or double precision number or function or variable before *' +run 0 '> 1 + 2 * * 3 +> err: 1.9: syntax error: expected - or ( or double precision number or function or variable before *' cat >input <<EOF 100% EOF -run 0 '100 -err: 1.4: error: invalid character' +run 0 '> 100% +100 +> err: 1.4: error: invalid character' cat >input <<EOF 1 / 0 EOF -run 0 'err: 1.1-5: error: division by zero' +run 0 '> 1 / 0 +> err: 1.1-5: error: division by zero' diff --git a/examples/c/bistromathic/local.mk b/examples/c/bistromathic/local.mk index 0a805f9d..920265f6 100644 --- a/examples/c/bistromathic/local.mk +++ b/examples/c/bistromathic/local.mk @@ -27,7 +27,7 @@ nodist_%C%_bistromathic_SOURCES = %D%/parse.y %D%/parse.h # Don't use gnulib's system headers. %C%_bistromathic_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D% -%C%_bistromathic_LDADD = -lm +%C%_bistromathic_LDADD = -lm -lreadline dist_bistromathic_DATA = %D%/parse.y %D%/Makefile %D%/README.md CLEANFILES += %D%/parse.[ch] %D%/parse.output diff --git a/examples/c/bistromathic/parse.y b/examples/c/bistromathic/parse.y index 39244f95..4591b64f 100644 --- a/examples/c/bistromathic/parse.y +++ b/examples/c/bistromathic/parse.y @@ -5,7 +5,11 @@ #include <math.h> // cos, sin, etc. #include <stddef.h> // ptrdiff_t #include <stdio.h> // printf + #include <stdlib.h> // calloc. #include <string.h> // strcmp + + #include <readline/readline.h> + #include <readline/history.h> } %code requires { @@ -31,18 +35,24 @@ } %code provides { - int yylex (YYSTYPE *yylval, YYLTYPE *yylloc); - void yyerror (YYLTYPE *yylloc, char const *); + int yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc); + void yyerror (YYLTYPE *yylloc, char const *msg); } %code { #define N_ #define _ + + // Whether to quit. + int done = 0; } // Don't share global variables between the scanner and the parser. %define api.pure full +// Generate a push parser. +%define api.push-pull push + // To avoid name clashes (e.g., with C's EOF) prefix token definitions // with TOK_ (e.g., TOK_EOF). %define api.token.prefix {TOK_} @@ -70,7 +80,7 @@ LPAREN "(" RPAREN ")" EQUAL "=" - EOL _("end of line") + EXIT "exit" EOF 0 _("end of file") <double> NUM _("double precision number") @@ -99,13 +109,8 @@ %% // The grammar follows. input: %empty -| input line -; - -line: - EOL -| exp EOL { printf ("%.10g\n", $exp); } -| error EOL { yyerrok; } +| exp { printf ("%.10g\n", $exp); } +| "exit" { done = 1; } ; exp: @@ -134,6 +139,11 @@ exp: // End of grammar. %% +#undef yyssp +#undef yyesa +#undef yyes +#undef yyes_capacity + /*------------. | Functions. | `------------*/ @@ -190,13 +200,23 @@ getsym (char const *name) return NULL; } +// How many symbols are registered. +int +symbol_count (void) +{ + int res = 0; + for (symrec *p = sym_table; p; p = p->next) + ++res; + return res; +} + /*----------. | Scanner. | `----------*/ int -yylex (YYSTYPE *yylval, YYLTYPE *yylloc) +yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc) { int c; @@ -207,7 +227,7 @@ yylex (YYSTYPE *yylval, YYLTYPE *yylloc) yylloc->first_column = yylloc->last_column; yylloc->last_column += 1; - c = getchar (); + c = *((*line)++); } while (c == ' ' || c == '\t'); switch (c) @@ -221,40 +241,42 @@ yylex (YYSTYPE *yylval, YYLTYPE *yylloc) case '(': return TOK_LPAREN; case ')': return TOK_RPAREN; - case '\n': - yylloc->last_column = 1; - yylloc->last_line += 1; - return TOK_EOL; + case 0: return TOK_EOF; - case EOF: return TOK_EOF; - - // Any other character is a token by itself. default: + // Numbers. if (c == '.' || isdigit (c)) { - ungetc (c, stdin); int nchars = 0; - scanf ("%lf%n", &yylval->TOK_NUM, &nchars); + sscanf (*line - 1, "%lf%n", &yylval->TOK_NUM, &nchars); + *line += nchars - 1; yylloc->last_column += nchars - 1; return TOK_NUM; } + // Identifiers. else if (islower (c)) { - ungetc (c, stdin); int nchars = 0; char buf[100]; - scanf ("%99[a-z]%n", buf, &nchars); - symrec *s = getsym (buf); - if (!s) - s = putsym (buf, TOK_VAR); - yylval->TOK_VAR = s; + sscanf (*line - 1, "%99[a-z]%n", buf, &nchars); + *line += nchars - 1; yylloc->last_column += nchars - 1; - return s->type; + if (strcmp (buf, "exit") == 0) + return TOK_EXIT; + else + { + symrec *s = getsym (buf); + if (!s) + s = putsym (buf, TOK_VAR); + yylval->TOK_VAR = s; + return s->type; + } } + // Stray characters. else { yyerror (yylloc, "error: invalid character"); - return yylex (yylval, yylloc); + return yylex (line, yylval, yylloc); } } } @@ -291,6 +313,126 @@ void yyerror (YYLTYPE *loc, char const *msg) } +/*-----------. +| Readline. | +`-----------*/ + +// Parse (and execute) this line. +int process_line (YYLTYPE *lloc, const char *line) +{ + yypstate *ps = yypstate_new (); + int status = 0; + do { + YYSTYPE lval; + status = yypush_parse (ps, yylex (&line, &lval, lloc), &lval, lloc); + } while (status == YYPUSH_MORE); + yypstate_delete (ps); + lloc->last_line++; + lloc->last_column = 1; + return status; +} + +// Get the list of possible tokens after INPUT was read. +int +expected_tokens (const char *input, + int *tokens, int ntokens) +{ + YYDPRINTF ((stderr, "expected_tokens(\"%s\")", input)); + + // Parse the current state of the line. + YYLTYPE lloc; + yypstate *ps = yypstate_new (); + int status = 0; + do { + if (!*input) + break; + YYSTYPE lval; + int token = yylex (&input, &lval, &lloc); + if (!token) + break; + status = yypush_parse (ps, token, &lval, &lloc); + } while (status == YYPUSH_MORE); + + // Then query for the accepted tokens at this point. + yyparse_context_t yyctx + = {ps->yyssp, YYEMPTY, &lloc, ps->yyesa, &ps->yyes, &ps->yyes_capacity}; + return yyexpected_tokens (&yyctx, tokens, ntokens); +} + +/* Attempt to complete on the contents of TEXT. START and END bound the + region of rl_line_buffer that contains the word to complete. TEXT is + the word to complete. We can use the entire contents of rl_line_buffer + in case we want to do some simple parsing. Return the array of matches, + or NULL if there aren't any. */ +char ** +completion (const char *text, int start, int end) +{ + YYDPRINTF ((stderr, "completion(\"%.*s[%.*s]%s\")\n", + start, rl_line_buffer, + end - start, rl_line_buffer + start, + rl_line_buffer + end)); + + // Get list of token numbers. + int tokens[YYNTOKENS]; + char *line = strndup (rl_line_buffer, start); + int ntokens = expected_tokens (line, tokens, YYNTOKENS); + free (line); + + // Build MATCHES, the list of possible completions. + const int len = strlen (text); + // Need initial prefix and final NULL. + char **matches = calloc (ntokens + symbol_count () + 2, sizeof *matches); + int match = 0; + matches[match++] = strdup (text); + for (int i = 0; i < ntokens; ++i) + if (tokens[i] == YYTRANSLATE (TOK_VAR)) + { + for (symrec *s = sym_table; s; s = s->next) + if (s->type == TOK_VAR && strncmp (text, s->name, len) == 0) + matches[match++] = strdup (s->name); + } + else if (tokens[i] == YYTRANSLATE (TOK_FUN)) + { + for (symrec *s = sym_table; s; s = s->next) + if (s->type == TOK_FUN && strncmp (text, s->name, len) == 0) + matches[match++] = strdup (s->name); + } + else + { + const char* token = yysymbol_name (tokens[i]); + if (strncmp (token, text, strlen (text)) == 0) + matches[match++] = strdup (token); + } + + if (yydebug) + { + fprintf (stderr, "completion(\"%.*s[%.*s]%s\") = ", + start, rl_line_buffer, + end - start, rl_line_buffer + start, + rl_line_buffer + end); + for (int i = 1; matches[i]; ++i) + fprintf (stderr, "%s%s", + i == 1 ? "{" : ", ", + matches[i]); + fprintf (stderr, "}\n"); + } + + // Don't fall back to proposing file names. + rl_attempted_completion_over = 1; + return matches; +} + +void init_readline (void) +{ + /* Allow conditional parsing of the ~/.inputrc file. */ + rl_readline_name = "pushcalc"; + + /* Tell the completer that we want a crack first. */ + rl_attempted_completion_function = completion; +} + + + /*-------. | Main. | `-------*/ @@ -301,5 +443,16 @@ int main (int argc, char const* argv[]) if (argc == 2 && strcmp(argv[1], "-p") == 0) yydebug = 1; init_table (); - return yyparse (); + init_readline (); + YYLTYPE lloc = {1, 1, 1, 1}; + while (!done) + { + char *line = readline ("> "); + if (!line) + return 0; + if (*line) + add_history (line); + process_line (&lloc, line); + free (line); + } } |