From 7a0693849ac589de8fc975a6ebb4602d3ef58732 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Sat, 2 Apr 2016 16:41:13 -0700 Subject: [PATCH] lexer: Add comments and update style in lex_source_get__(). --- src/language/lexer/lexer.c | 86 +++++++++++++++++++++----------------- 1 file changed, 47 insertions(+), 39 deletions(-) diff --git a/src/language/lexer/lexer.c b/src/language/lexer/lexer.c index b6cab8d681..ea81f19559 100644 --- a/src/language/lexer/lexer.c +++ b/src/language/lexer/lexer.c @@ -1,5 +1,5 @@ /* PSPP - a program for statistical analysis. - Copyright (C) 1997-9, 2000, 2006, 2009, 2010, 2011, 2013 Free Software Foundation, Inc. + Copyright (C) 1997-9, 2000, 2006, 2009, 2010, 2011, 2013, 2016 Free Software Foundation, Inc. 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 @@ -184,7 +184,7 @@ lex_append (struct lexer *lexer, struct lex_reader *reader) ll_push_tail (&lexer->sources, &lex_source_create (reader)->ll); } -/* Advacning. */ +/* Advancing. */ static struct lex_token * lex_push_token__ (struct lex_source *src) @@ -1315,37 +1315,44 @@ lex_get_error (struct lex_source *src, const char *format, ...) va_end (args); } +/* Attempts to append an additional token into SRC's deque, reading more from + the underlying lex_reader if necessary.. Returns true if successful, false + if the deque already represents (a suffix of) the whole lex_reader's + contents, */ static bool lex_source_get__ (const struct lex_source *src_) { struct lex_source *src = CONST_CAST (struct lex_source *, src_); + if (src->eof) + return false; + /* State maintained while scanning tokens. Usually we only need a single + state, but scanner_push() can return SCAN_SAVE to indicate that the state + needs to be saved and possibly restored later with SCAN_BACK. */ struct state { struct segmenter segmenter; enum segment_type last_segment; - int newlines; + int newlines; /* Number of newlines encountered so far. */ + /* Maintained here so we can update lex_source's similar members when we + finish. */ size_t line_pos; size_t seg_pos; }; - struct state state, saved; - enum scan_result result; - struct scanner scanner; - struct lex_token *token; - int n_lines; - int i; - - if (src->eof) - return false; - - state.segmenter = src->segmenter; - state.newlines = 0; - state.seg_pos = src->seg_pos; - state.line_pos = src->line_pos; - saved = state; + /* Initialize state. */ + struct state state = + { + .segmenter = src->segmenter, + .newlines = 0, + .seg_pos = src->seg_pos, + .line_pos = src->line_pos, + }; + struct state saved = state; - token = lex_push_token__ (src); + /* Append a new token to SRC and initialize it. */ + struct lex_token *token = lex_push_token__ (src); + struct scanner scanner; scanner_init (&scanner, &token->token); token->line_pos = src->line_pos; token->token_pos = src->seg_pos; @@ -1354,22 +1361,24 @@ lex_source_get__ (const struct lex_source *src_) else token->first_line = 0; + /* Extract segments and pass them through the scanner until we obtain a + token. */ for (;;) { + /* Extract a segment. */ + const char *segment = &src->buffer[state.seg_pos - src->tail]; + size_t seg_maxlen = src->head - state.seg_pos; enum segment_type type; - const char *segment; - size_t seg_maxlen; - int seg_len; - - segment = &src->buffer[state.seg_pos - src->tail]; - seg_maxlen = src->head - state.seg_pos; - seg_len = segmenter_push (&state.segmenter, segment, seg_maxlen, &type); + int seg_len = segmenter_push (&state.segmenter, segment, seg_maxlen, + &type); if (seg_len < 0) { + /* The segmenter needs more input to produce a segment. */ lex_source_read__ (src); continue; } + /* Update state based on the segment. */ state.last_segment = type; state.seg_pos += seg_len; if (type == SEG_NEWLINE) @@ -1378,8 +1387,10 @@ lex_source_get__ (const struct lex_source *src_) state.line_pos = state.seg_pos; } - result = scanner_push (&scanner, type, ss_buffer (segment, seg_len), - &token->token); + /* Pass the segment into the scanner and try to get a token out. */ + enum scan_result result = scanner_push (&scanner, type, + ss_buffer (segment, seg_len), + &token->token); if (result == SCAN_SAVE) saved = state; else if (result == SCAN_BACK) @@ -1391,7 +1402,9 @@ lex_source_get__ (const struct lex_source *src_) break; } - n_lines = state.newlines; + /* If we've reached the end of a line, or the end of a command, then pass + the line to the output engine as a syntax text item. */ + int n_lines = state.newlines; if (state.last_segment == SEG_END_COMMAND && !src->suppress_next_newline) { n_lines++; @@ -1402,20 +1415,15 @@ lex_source_get__ (const struct lex_source *src_) n_lines--; src->suppress_next_newline = false; } - for (i = 0; i < n_lines; i++) + for (int i = 0; i < n_lines; i++) { - const char *newline; - const char *line; - size_t line_len; - char *syntax; - - line = &src->buffer[src->journal_pos - src->tail]; - newline = rawmemchr (line, '\n'); - line_len = newline - line; + const char *line = &src->buffer[src->journal_pos - src->tail]; + const char *newline = rawmemchr (line, '\n'); + size_t line_len = newline - line; if (line_len > 0 && line[line_len - 1] == '\r') line_len--; - syntax = malloc (line_len + 2); + char *syntax = malloc (line_len + 2); memcpy (syntax, line, line_len); syntax[line_len] = '\n'; syntax[line_len + 1] = '\0'; -- 2.30.2