- Win32 has no strings.h
[cparser] / lexer.c
diff --git a/lexer.c b/lexer.c
index 749db3d..4efc5bb 100644 (file)
--- a/lexer.c
+++ b/lexer.c
@@ -1,7 +1,27 @@
+/*
+ * This file is part of cparser.
+ * Copyright (C) 2007-2008 Matthias Braun <matze@braunis.de>
+ *
+ * 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 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
 #include <config.h>
 
 #include "diagnostic.h"
 #include "lexer.h"
+#include "symbol_t.h"
 #include "token_t.h"
 #include "symbol_table_t.h"
 #include "adt/error.h"
@@ -12,6 +32,7 @@
 #include "target_architecture.h"
 #include "parser.h"
 #include "warning.h"
+#include "lang_features.h"
 
 #include <assert.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <ctype.h>
 
+#ifndef _WIN32
+#include <strings.h>
+#endif
+
 //#define DEBUG_CHARS
 #define MAX_PUTBACK 3
+#define BUF_SIZE    1024
 
-#ifdef _WIN32
+#if defined(_WIN32) || defined(__CYGWIN__)
 /* No strtold on windows and no replacement yet */
-#define strtold(s, e) strtod(s, e)
+#define strtold(s, e)     strtod(s, e)
+#define strcasecmp(a, b)  stricmp(a, b)
 #endif
 
-#if defined HAS_SIGNED_CHAR
-typedef signed char char_type;
-#elif defined HAS_UNSIGNED_CHAR
-typedef unsigned char char_type;
-#else
-#      error signedness of char not determined
-#endif
+typedef unsigned int utf32;
 
-static int         c;
-token_t            lexer_token;
-symbol_t          *symbol_L;
-static FILE       *input;
-static char        buf[1024 + MAX_PUTBACK];
-static const char *bufend;
-static const char *bufpos;
-static strset_t    stringset;
+static utf32        c;
+token_t             lexer_token;
+symbol_t           *symbol_L;
+static FILE        *input;
+static utf32        buf[BUF_SIZE + MAX_PUTBACK];
+static const utf32 *bufend;
+static const utf32 *bufpos;
+static strset_t     stringset;
+bool                allow_dollar_in_symbol = true;
 
 /**
  * Prints a parse error message at the current token.
@@ -51,32 +73,255 @@ static strset_t    stringset;
  */
 static void parse_error(const char *msg)
 {
-       errorf(lexer_token.source_position,  "%s", msg);
+       errorf(&lexer_token.source_position, "%s", msg);
+}
+
+/**
+ * Prints an internal error message at the current token.
+ *
+ * @param msg   the error message
+ */
+static NORETURN internal_error(const char *msg)
+{
+       internal_errorf(&lexer_token.source_position, "%s", msg);
+}
+
+static size_t read_block(unsigned char *const read_buf, size_t const n)
+{
+       size_t const s = fread(read_buf, 1, n, input);
+       if (s == 0) {
+               if (ferror(input))
+                       parse_error("read from input failed");
+               buf[MAX_PUTBACK] = EOF;
+               bufpos           = buf + MAX_PUTBACK;
+               bufend           = buf + MAX_PUTBACK + 1;
+       }
+       return s;
+}
+
+static void decode_iso_8859_1(void)
+{
+       unsigned char read_buf[BUF_SIZE];
+       size_t const s = read_block(read_buf, sizeof(read_buf));
+       if (s == 0)
+               return;
+
+       unsigned char const *src = read_buf;
+       unsigned char const *end = read_buf + s;
+       utf32               *dst = buf + MAX_PUTBACK;
+       while (src != end)
+               *dst++ = *src++;
+
+       bufpos = buf + MAX_PUTBACK;
+       bufend = dst;
+}
+
+static void decode_iso_8859_15(void)
+{
+       unsigned char read_buf[BUF_SIZE];
+       size_t const s = read_block(read_buf, sizeof(read_buf));
+       if (s == 0)
+               return;
+
+       unsigned char const *src = read_buf;
+       unsigned char const *end = read_buf + s;
+       utf32               *dst = buf + MAX_PUTBACK;
+       while (src != end) {
+               utf32 tc = *src++;
+               switch (tc) {
+                       case 0xA4: tc = 0x20AC; break; // €
+                       case 0xA6: tc = 0x0160; break; // Š
+                       case 0xA8: tc = 0x0161; break; // š
+                       case 0xB4: tc = 0x017D; break; // Ž
+                       case 0xB8: tc = 0x017E; break; // ž
+                       case 0xBC: tc = 0x0152; break; // Œ
+                       case 0xBD: tc = 0x0153; break; // œ
+                       case 0xBE: tc = 0x0178; break; // Ÿ
+               }
+               *dst++ = tc;
+       }
+
+       bufpos = buf + MAX_PUTBACK;
+       bufend = dst;
+}
+
+static void decode_utf8(void)
+{
+       static utf32  part_decoded_min_code;
+       static utf32  part_decoded_char;
+       static size_t part_decoded_rest_len;
+
+       do {
+               unsigned char read_buf[BUF_SIZE];
+               size_t const s = read_block(read_buf, sizeof(read_buf));
+               if (s == 0) {
+                       if (part_decoded_rest_len > 0)
+                               parse_error("incomplete input char at end of input");
+                       return;
+               }
+
+               unsigned char const *src = read_buf;
+               unsigned char const *end = read_buf + s;
+               utf32               *dst = buf + MAX_PUTBACK;
+               utf32                decoded;
+               utf32                min_code;
+
+               if (part_decoded_rest_len != 0) {
+                       min_code              = part_decoded_min_code;
+                       decoded               = part_decoded_char;
+                       size_t const rest_len = part_decoded_rest_len;
+                       part_decoded_rest_len = 0;
+                       switch (rest_len) {
+                               case 4:  goto realign;
+                               case 3:  goto three_more;
+                               case 2:  goto two_more;
+                               default: goto one_more;
+                       }
+               }
+
+               while (src != end) {
+                       if ((*src & 0x80) == 0) {
+                               decoded = *src++;
+                       } else if ((*src & 0xE0) == 0xC0) {
+                               min_code = 0x80;
+                               decoded  = *src++ & 0x1F;
+one_more:
+                               if (src == end) {
+                                       part_decoded_min_code = min_code;
+                                       part_decoded_char     = decoded;
+                                       part_decoded_rest_len = 1;
+                                       break;
+                               }
+                               if ((*src & 0xC0) == 0x80) {
+                                       decoded = (decoded << 6) | (*src++ & 0x3F);
+                               } else {
+                                       goto invalid_char;
+                               }
+                               if (decoded < min_code                      ||
+                                               decoded > 0x10FFFF                      ||
+                                               (0xD800 <= decoded && decoded < 0xE000) || // high/low surrogates
+                                               (0xFDD0 <= decoded && decoded < 0xFDF0) || // noncharacters
+                                               (decoded & 0xFFFE) == 0xFFFE) {            // noncharacters
+                                       parse_error("invalid byte sequence in input");
+                               }
+                       } else if ((*src & 0xF0) == 0xE0) {
+                               min_code = 0x800;
+                               decoded  = *src++ & 0x0F;
+two_more:
+                               if (src == end) {
+                                       part_decoded_min_code = min_code;
+                                       part_decoded_char     = decoded;
+                                       part_decoded_rest_len = 2;
+                                       break;
+                               }
+                               if ((*src & 0xC0) == 0x80) {
+                                       decoded = (decoded << 6) | (*src++ & 0x3F);
+                               } else {
+                                       goto invalid_char;
+                               }
+                               goto one_more;
+                       } else if ((*src & 0xF8) == 0xF0) {
+                               min_code = 0x10000;
+                               decoded  = *src++ & 0x07;
+three_more:
+                               if (src == end) {
+                                       part_decoded_min_code = min_code;
+                                       part_decoded_char     = decoded;
+                                       part_decoded_rest_len = 3;
+                                       break;
+                               }
+                               if ((*src & 0xC0) == 0x80) {
+                                       decoded = (decoded << 6) | (*src++ & 0x3F);
+                               } else {
+                                       goto invalid_char;
+                               }
+                               goto two_more;
+                       } else {
+invalid_char:
+                               parse_error("invalid byte sequence in input");
+realign:
+                               do {
+                                       ++src;
+                                       if (src == end) {
+                                               part_decoded_rest_len = 4;
+                                               break;
+                                       }
+                               } while ((*src & 0xC0) == 0x80 || (*src & 0xF8) == 0xF8);
+                               continue;
+                       }
+                       *dst++ = decoded;
+               }
+
+               bufpos = buf + MAX_PUTBACK;
+               bufend = dst;
+       } while (bufpos == bufend);
+}
+
+typedef void (*decoder_t)(void);
+
+static decoder_t decoder = decode_utf8;
+
+typedef struct named_decoder_t {
+       char const *name;
+       decoder_t   decoder;
+} named_decoder_t;
+
+static named_decoder_t const decoders[] = {
+       { "CP819",           decode_iso_8859_1  }, // offical alias
+       { "IBM819",          decode_iso_8859_1  }, // offical alias
+       { "ISO-8859-1",      decode_iso_8859_1  }, // offical alias
+       { "ISO-8859-15",     decode_iso_8859_15 }, // offical name
+       { "ISO8859-1",       decode_iso_8859_1  },
+       { "ISO8859-15",      decode_iso_8859_15 },
+       { "ISO_8859-1",      decode_iso_8859_1  }, // offical alias
+       { "ISO_8859-15",     decode_iso_8859_15 }, // offical alias
+       { "ISO_8859-1:1987", decode_iso_8859_1  }, // offical name
+       { "Latin-9",         decode_iso_8859_15 }, // offical alias
+       { "UTF-8",           decode_utf8        }, // offical name
+       { "csISOLatin1",     decode_iso_8859_1  }, // offical alias
+       { "iso-ir-100",      decode_iso_8859_1  }, // offical alias
+       { "l1",              decode_iso_8859_1  }, // offical alias
+       { "latin1",          decode_iso_8859_1  }, // offical alias
+
+       { NULL,              NULL               }
+};
+
+void select_input_encoding(char const* const encoding)
+{
+       for (named_decoder_t const *i = decoders; i->name != NULL; ++i) {
+               if (strcasecmp(encoding, i->name) != 0)
+                       continue;
+               decoder = i->decoder;
+               return;
+       }
+       fprintf(stderr, "error: input encoding \"%s\" not supported\n", encoding);
 }
 
 static inline void next_real_char(void)
 {
        assert(bufpos <= bufend);
        if (bufpos >= bufend) {
-               size_t s = fread(buf + MAX_PUTBACK, 1, sizeof(buf) - MAX_PUTBACK,
-                                input);
-               if(s == 0) {
+               if (input == NULL) {
                        c = EOF;
                        return;
                }
-               bufpos = buf + MAX_PUTBACK;
-               bufend = buf + MAX_PUTBACK + s;
+               decoder();
        }
        c = *bufpos++;
 }
 
-static inline void put_back(int pc)
+/**
+ * Put a character back into the buffer.
+ *
+ * @param pc  the character to put back
+ */
+static inline void put_back(utf32 const pc)
 {
        assert(bufpos > buf);
-       *(--bufpos - buf + buf) = (char) pc;
+       *(--bufpos - buf + buf) = pc;
 
 #ifdef DEBUG_CHARS
-       printf("putback '%c'\n", pc);
+       printf("putback '%lc'\n", pc);
 #endif
 }
 
@@ -112,6 +357,10 @@ static void maybe_concat_lines(void)
        c = '\\';
 }
 
+/**
+ * Set c to the next input character, ie.
+ * after expanding trigraphs.
+ */
 static inline void next_char(void)
 {
        next_real_char();
@@ -157,6 +406,7 @@ end_of_next_char:;
 }
 
 #define SYMBOL_CHARS  \
+       case '$': if (!allow_dollar_in_symbol) goto dollar_sign; \
        case 'a':         \
        case 'b':         \
        case 'c':         \
@@ -223,6 +473,10 @@ end_of_next_char:;
        case '8':         \
        case '9':
 
+/**
+ * Read a symbol from the input and build
+ * the lexer_token.
+ */
 static void parse_symbol(void)
 {
        symbol_t *symbol;
@@ -240,6 +494,7 @@ static void parse_symbol(void)
                        break;
 
                default:
+dollar_sign:
                        goto end_symbol;
                }
        }
@@ -260,60 +515,78 @@ end_symbol:
 
 static void parse_integer_suffix(bool is_oct_hex)
 {
-       bool is_unsigned  = false;
-       bool min_long     = false;
-       bool min_longlong = false;
-
-       if(c == 'U' || c == 'u') {
-               is_unsigned = true;
+       bool is_unsigned     = false;
+       bool min_long        = false;
+       bool min_longlong    = false;
+       bool not_traditional = false;
+       int  pos             = 0;
+       char suffix[4];
+
+       if (c == 'U' || c == 'u') {
+               not_traditional = true;
+               suffix[pos++]   = toupper(c);
+               is_unsigned     = true;
                next_char();
-               if(c == 'L' || c == 'l') {
+               if (c == 'L' || c == 'l') {
+                       suffix[pos++] = toupper(c);
                        min_long = true;
                        next_char();
-                       if(c == 'L' || c == 'l') {
+                       if (c == 'L' || c == 'l') {
+                               suffix[pos++] = toupper(c);
                                min_longlong = true;
                                next_char();
                        }
                }
-       } else if(c == 'l' || c == 'L') {
+       } else if (c == 'l' || c == 'L') {
+               suffix[pos++] = toupper(c);
                min_long = true;
                next_char();
-               if(c == 'l' || c == 'L') {
-                       min_longlong = true;
+               if (c == 'l' || c == 'L') {
+                       not_traditional = true;
+                       suffix[pos++]   = toupper(c);
+                       min_longlong    = true;
                        next_char();
-                       if(c == 'u' || c == 'U') {
-                               is_unsigned = true;
+                       if (c == 'u' || c == 'U') {
+                               suffix[pos++] = toupper(c);
+                               is_unsigned   = true;
                                next_char();
                        }
-               } else if(c == 'u' || c == 'U') {
-                       is_unsigned = true;
+               } else if (c == 'u' || c == 'U') {
+                       not_traditional = true;
+                       suffix[pos++]   = toupper(c);
+                       is_unsigned     = true;
                        next_char();
                        lexer_token.datatype = type_unsigned_long;
                }
        }
 
-       if(!is_unsigned) {
+       if (warning.traditional && not_traditional) {
+               suffix[pos] = '\0';
+               warningf(&lexer_token.source_position,
+                       "traditional C rejects the '%s' suffix", suffix);
+       }
+       if (!is_unsigned) {
                long long v = lexer_token.v.intvalue;
-               if(!min_long) {
-                       if(v >= TARGET_INT_MIN && v <= TARGET_INT_MAX) {
+               if (!min_long) {
+                       if (v >= TARGET_INT_MIN && v <= TARGET_INT_MAX) {
                                lexer_token.datatype = type_int;
                                return;
-                       } else if(is_oct_hex && v >= 0 && v <= TARGET_UINT_MAX) {
+                       } else if (is_oct_hex && v >= 0 && v <= TARGET_UINT_MAX) {
                                lexer_token.datatype = type_unsigned_int;
                                return;
                        }
                }
-               if(!min_longlong) {
-                       if(v >= TARGET_LONG_MIN && v <= TARGET_LONG_MAX) {
+               if (!min_longlong) {
+                       if (v >= TARGET_LONG_MIN && v <= TARGET_LONG_MAX) {
                                lexer_token.datatype = type_long;
                                return;
-                       } else if(is_oct_hex && v >= 0 && v <= TARGET_ULONG_MAX) {
+                       } else if (is_oct_hex && v >= 0 && (unsigned long long)v <= (unsigned long long)TARGET_ULONG_MAX) {
                                lexer_token.datatype = type_unsigned_long;
                                return;
                        }
                }
                unsigned long long uv = (unsigned long long) v;
-               if(is_oct_hex && uv > (unsigned long long) TARGET_LONGLONG_MAX) {
+               if (is_oct_hex && uv > (unsigned long long) TARGET_LONGLONG_MAX) {
                        lexer_token.datatype = type_unsigned_long_long;
                        return;
                }
@@ -321,11 +594,11 @@ static void parse_integer_suffix(bool is_oct_hex)
                lexer_token.datatype = type_long_long;
        } else {
                unsigned long long v = (unsigned long long) lexer_token.v.intvalue;
-               if(!min_long && v <= TARGET_UINT_MAX) {
+               if (!min_long && v <= TARGET_UINT_MAX) {
                        lexer_token.datatype = type_unsigned_int;
                        return;
                }
-               if(!min_longlong && v <= TARGET_ULONG_MAX) {
+               if (!min_longlong && v <= TARGET_ULONG_MAX) {
                        lexer_token.datatype = type_unsigned_long;
                        return;
                }
@@ -336,14 +609,22 @@ static void parse_integer_suffix(bool is_oct_hex)
 static void parse_floating_suffix(void)
 {
        switch(c) {
-       /* TODO: do something usefull with the suffixes... */
+       /* TODO: do something useful with the suffixes... */
        case 'f':
        case 'F':
+               if (warning.traditional) {
+                       warningf(&lexer_token.source_position,
+                               "traditional C rejects the 'F' suffix");
+               }
                next_char();
                lexer_token.datatype = type_float;
                break;
        case 'l':
        case 'L':
+               if (warning.traditional) {
+                       warningf(&lexer_token.source_position,
+                               "traditional C rejects the 'F' suffix");
+               }
                next_char();
                lexer_token.datatype = type_long_double;
                break;
@@ -357,7 +638,8 @@ static void parse_floating_suffix(void)
  * A replacement for strtoull. Only those parts needed for
  * our parser are implemented.
  */
-static unsigned long long parse_int_string(const char *s, const char **endptr, int base) {
+static unsigned long long parse_int_string(const char *s, const char **endptr, int base)
+{
        unsigned long long v = 0;
 
        switch (base) {
@@ -437,43 +719,107 @@ end:
        return v;
 }
 
+/**
+ * Parses a hex number including hex floats and set the
+ * lexer_token.
+ */
 static void parse_number_hex(void)
 {
+       bool is_float = false;
        assert(c == 'x' || c == 'X');
        next_char();
 
+       obstack_1grow(&symbol_obstack, '0');
+       obstack_1grow(&symbol_obstack, 'x');
+
        while(isxdigit(c)) {
                obstack_1grow(&symbol_obstack, (char) c);
                next_char();
        }
-       obstack_1grow(&symbol_obstack, '\0');
-       char *string = obstack_finish(&symbol_obstack);
 
-       if(c == '.' || c == 'p' || c == 'P') {
+       if (c == '.') {
+               obstack_1grow(&symbol_obstack, (char) c);
                next_char();
-               panic("Hex floating point numbers not implemented yet");
+
+               while (isxdigit(c)) {
+                       obstack_1grow(&symbol_obstack, (char) c);
+                       next_char();
+               }
+               is_float = true;
+       }
+       if (c == 'p' || c == 'P') {
+               obstack_1grow(&symbol_obstack, (char) c);
+               next_char();
+
+               if (c == '-' || c == '+') {
+                       obstack_1grow(&symbol_obstack, (char) c);
+                       next_char();
+               }
+
+               while (isxdigit(c)) {
+                       obstack_1grow(&symbol_obstack, (char) c);
+                       next_char();
+               }
+               is_float = true;
        }
+
+       obstack_1grow(&symbol_obstack, '\0');
+       char *string = obstack_finish(&symbol_obstack);
        if(*string == '\0') {
                parse_error("invalid hex number");
                lexer_token.type = T_ERROR;
+               obstack_free(&symbol_obstack, string);
+               return;
        }
 
-       const char *endptr;
-       lexer_token.type       = T_INTEGER;
-       lexer_token.v.intvalue = parse_int_string(string, &endptr, 16);
-       if(*endptr != '\0') {
-               parse_error("hex number literal too long");
+       if (is_float) {
+               char *endptr;
+               lexer_token.type         = T_FLOATINGPOINT;
+               lexer_token.v.floatvalue = strtold(string, &endptr);
+
+               if(*endptr != '\0') {
+                       parse_error("invalid hex float literal");
+               }
+
+               parse_floating_suffix();
+       } else {
+               const char *endptr;
+               lexer_token.type       = T_INTEGER;
+               lexer_token.v.intvalue = parse_int_string(string + 2, &endptr, 16);
+               if(*endptr != '\0') {
+                       parse_error("hex number literal too long");
+               }
+               parse_integer_suffix(true);
        }
 
        obstack_free(&symbol_obstack, string);
-       parse_integer_suffix(true);
 }
 
-static inline bool is_octal_digit(int chr)
+/**
+ * Returns true if the given char is a octal digit.
+ *
+ * @param char  the character to check
+ */
+static inline bool is_octal_digit(utf32 chr)
 {
-       return '0' <= chr && chr <= '7';
+       switch(chr) {
+       case '0':
+       case '1':
+       case '2':
+       case '3':
+       case '4':
+       case '5':
+       case '6':
+       case '7':
+               return true;
+       default:
+               return false;
+       }
 }
 
+/**
+ * Parses a octal number and set the lexer_token.
+ */
 static void parse_number_oct(void)
 {
        while(is_octal_digit(c)) {
@@ -494,26 +840,30 @@ static void parse_number_oct(void)
        parse_integer_suffix(true);
 }
 
+/**
+ * Parses a decimal including float number and set the
+ * lexer_token.
+ */
 static void parse_number_dec(void)
 {
        bool is_float = false;
-       while(isdigit(c)) {
+       while (isdigit(c)) {
                obstack_1grow(&symbol_obstack, (char) c);
                next_char();
        }
 
-       if(c == '.') {
+       if (c == '.') {
                obstack_1grow(&symbol_obstack, '.');
                next_char();
 
-               while(isdigit(c)) {
+               while (isdigit(c)) {
                        obstack_1grow(&symbol_obstack, (char) c);
                        next_char();
                }
                is_float = true;
        }
        if(c == 'e' || c == 'E') {
-               obstack_1grow(&symbol_obstack, 'e');
+               obstack_1grow(&symbol_obstack, (char) c);
                next_char();
 
                if(c == '-' || c == '+') {
@@ -555,6 +905,9 @@ static void parse_number_dec(void)
        obstack_free(&symbol_obstack, string);
 }
 
+/**
+ * Parses a number and sets the lexer_token.
+ */
 static void parse_number(void)
 {
        if (c == '0') {
@@ -593,46 +946,82 @@ static void parse_number(void)
        }
 }
 
-static int parse_octal_sequence(const int first_digit)
+/**
+ * Returns the value of a digit.
+ * The only portable way to do it ...
+ */
+static int digit_value(utf32 const digit)
+{
+       switch (digit) {
+       case '0': return 0;
+       case '1': return 1;
+       case '2': return 2;
+       case '3': return 3;
+       case '4': return 4;
+       case '5': return 5;
+       case '6': return 6;
+       case '7': return 7;
+       case '8': return 8;
+       case '9': return 9;
+       case 'a':
+       case 'A': return 10;
+       case 'b':
+       case 'B': return 11;
+       case 'c':
+       case 'C': return 12;
+       case 'd':
+       case 'D': return 13;
+       case 'e':
+       case 'E': return 14;
+       case 'f':
+       case 'F': return 15;
+       default:
+               internal_error("wrong character given");
+       }
+}
+
+/**
+ * Parses an octal character sequence.
+ *
+ * @param first_digit  the already read first digit
+ */
+static utf32 parse_octal_sequence(utf32 const first_digit)
 {
        assert(is_octal_digit(first_digit));
-       int value = first_digit - '0';
+       utf32 value = digit_value(first_digit);
        if (!is_octal_digit(c)) return value;
-       value = 8 * value + c - '0';
+       value = 8 * value + digit_value(c);
        next_char();
        if (!is_octal_digit(c)) return value;
-       value = 8 * value + c - '0';
+       value = 8 * value + digit_value(c);
        next_char();
-       return (char_type)value;
+       return value;
 }
 
-static int parse_hex_sequence(void)
+/**
+ * Parses a hex character sequence.
+ */
+static utf32 parse_hex_sequence(void)
 {
-       int value = 0;
-       while(1) {
-               if (c >= '0' && c <= '9') {
-                       value = 16 * value + c - '0';
-               } else if ('A' <= c && c <= 'F') {
-                       value = 16 * value + c - 'A' + 10;
-               } else if ('a' <= c && c <= 'f') {
-                       value = 16 * value + c - 'a' + 10;
-               } else {
-                       break;
-               }
+       utf32 value = 0;
+       while(isxdigit(c)) {
+               value = 16 * value + digit_value(c);
                next_char();
        }
-
-       return (char_type)value;
+       return value;
 }
 
-static int parse_escape_sequence(void)
+/**
+ * Parse an escape sequence.
+ */
+static utf32 parse_escape_sequence(void)
 {
        eat('\\');
 
-       int ec = c;
+       utf32 const ec = c;
        next_char();
 
-       switch(ec) {
+       switch (ec) {
        case '"':  return '"';
        case '\'': return '\'';
        case '\\': return '\\';
@@ -658,12 +1047,23 @@ static int parse_escape_sequence(void)
        case EOF:
                parse_error("reached end of file while parsing escape sequence");
                return EOF;
+       /* \E is not documented, but handled, by GCC.  It is acceptable according
+        * to §6.11.4, whereas \e is not. */
+       case 'E':
+       case 'e':
+               if (c_mode & _GNUC)
+                       return 27;   /* hopefully 27 is ALWAYS the code for ESCAPE */
+               /* FALLTHROUGH */
        default:
+               /* §6.4.4.4:8 footnote 64 */
                parse_error("unknown escape sequence");
                return EOF;
        }
 }
 
+/**
+ * Concatenate two strings.
+ */
 string_t concat_strings(const string_t *const s1, const string_t *const s2)
 {
        const size_t len1 = s1->size - 1;
@@ -673,6 +1073,10 @@ string_t concat_strings(const string_t *const s1, const string_t *const s2)
        memcpy(concat, s1->begin, len1);
        memcpy(concat + len1, s2->begin, len2 + 1);
 
+       if (warning.traditional) {
+               warningf(&lexer_token.source_position,
+                       "traditional C rejects string constant concatenation");
+       }
 #if 0 /* TODO hash */
        const char *result = strset_insert(&stringset, concat);
        if(result != concat) {
@@ -685,6 +1089,9 @@ string_t concat_strings(const string_t *const s1, const string_t *const s2)
 #endif
 }
 
+/**
+ * Concatenate a string and a wide string.
+ */
 wide_string_t concat_string_wide_string(const string_t *const s1, const wide_string_t *const s2)
 {
        const size_t len1 = s1->size - 1;
@@ -696,10 +1103,17 @@ wide_string_t concat_string_wide_string(const string_t *const s1, const wide_str
                concat[i] = src[i];
        }
        memcpy(concat + len1, s2->begin, (len2 + 1) * sizeof(*concat));
+       if (warning.traditional) {
+               warningf(&lexer_token.source_position,
+                       "traditional C rejects string constant concatenation");
+       }
 
        return (wide_string_t){ concat, len1 + len2 + 1 };
 }
 
+/**
+ * Concatenate two wide strings.
+ */
 wide_string_t concat_wide_strings(const wide_string_t *const s1, const wide_string_t *const s2)
 {
        const size_t len1 = s1->size - 1;
@@ -708,10 +1122,17 @@ wide_string_t concat_wide_strings(const wide_string_t *const s1, const wide_stri
        wchar_rep_t *const concat = obstack_alloc(&symbol_obstack, (len1 + len2 + 1) * sizeof(*concat));
        memcpy(concat,        s1->begin, len1       * sizeof(*concat));
        memcpy(concat + len1, s2->begin, (len2 + 1) * sizeof(*concat));
+       if (warning.traditional) {
+               warningf(&lexer_token.source_position,
+                       "traditional C rejects string constant concatenation");
+       }
 
        return (wide_string_t){ concat, len1 + len2 + 1 };
 }
 
+/**
+ * Concatenate a wide string and a string.
+ */
 wide_string_t concat_wide_string_string(const wide_string_t *const s1, const string_t *const s2)
 {
        const size_t len1 = s1->size - 1;
@@ -719,33 +1140,65 @@ wide_string_t concat_wide_string_string(const wide_string_t *const s1, const str
 
        wchar_rep_t *const concat = obstack_alloc(&symbol_obstack, (len1 + len2 + 1) * sizeof(*concat));
        memcpy(concat, s1->begin, len1 * sizeof(*concat));
-       const char *const src = s2->begin;
+       const char  *const src = s2->begin;
+       wchar_rep_t *const dst = concat + len1;
        for (size_t i = 0; i != len2 + 1; ++i) {
-               concat[i] = src[i];
+               dst[i] = src[i];
+       }
+       if (warning.traditional) {
+               warningf(&lexer_token.source_position,
+                       "traditional C rejects string constant concatenation");
        }
 
        return (wide_string_t){ concat, len1 + len2 + 1 };
 }
 
+static void grow_symbol(utf32 const tc)
+{
+       struct obstack *const o  = &symbol_obstack;
+       if (tc < 0x80U) {
+               obstack_1grow(o, tc);
+       } else if (tc < 0x800) {
+               obstack_1grow(o, 0xC0 | (tc >> 6));
+               obstack_1grow(o, 0x80 | (tc & 0x3F));
+       } else if (tc < 0x10000) {
+               obstack_1grow(o, 0xE0 | ( tc >> 12));
+               obstack_1grow(o, 0x80 | ((tc >>  6) & 0x3F));
+               obstack_1grow(o, 0x80 | ( tc        & 0x3F));
+       } else {
+               obstack_1grow(o, 0xF0 | ( tc >> 18));
+               obstack_1grow(o, 0x80 | ((tc >> 12) & 0x3F));
+               obstack_1grow(o, 0x80 | ((tc >>  6) & 0x3F));
+               obstack_1grow(o, 0x80 | ( tc        & 0x3F));
+       }
+}
+
+/**
+ * Parse a string literal and set lexer_token.
+ */
 static void parse_string_literal(void)
 {
        const unsigned start_linenr = lexer_token.source_position.linenr;
 
        eat('"');
 
-       int tc;
        while(1) {
                switch(c) {
-               case '\\':
-                       tc = parse_escape_sequence();
-                       obstack_1grow(&symbol_obstack, (char) tc);
+               case '\\': {
+                       utf32 const tc = parse_escape_sequence();
+                       if (tc >= 0x100) {
+                               warningf(&lexer_token.source_position,
+                                               "escape sequence out of range");
+                       }
+                       obstack_1grow(&symbol_obstack, tc);
                        break;
+               }
 
                case EOF: {
                        source_position_t source_position;
                        source_position.input_name = lexer_token.source_position.input_name;
                        source_position.linenr     = start_linenr;
-                       errorf(source_position, "string has no end");
+                       errorf(&source_position, "string has no end");
                        lexer_token.type = T_ERROR;
                        return;
                }
@@ -755,7 +1208,7 @@ static void parse_string_literal(void)
                        goto end_of_string;
 
                default:
-                       obstack_1grow(&symbol_obstack, (char) c);
+                       grow_symbol(c);
                        next_char();
                        break;
                }
@@ -785,16 +1238,22 @@ end_of_string:
        lexer_token.v.string.size  = size;
 }
 
+/**
+ * Parse a wide character constant and set lexer_token.
+ */
 static void parse_wide_character_constant(void)
 {
+       const unsigned start_linenr = lexer_token.source_position.linenr;
+
        eat('\'');
 
-       int found_char = 0;
        while(1) {
                switch(c) {
-               case '\\':
-                       found_char = parse_escape_sequence();
+               case '\\': {
+                       wchar_rep_t tc = parse_escape_sequence();
+                       obstack_grow(&symbol_obstack, &tc, sizeof(tc));
                        break;
+               }
 
                MATCH_NEWLINE(
                        parse_error("newline while parsing character constant");
@@ -805,30 +1264,39 @@ static void parse_wide_character_constant(void)
                        next_char();
                        goto end_of_wide_char_constant;
 
-               case EOF:
-                       parse_error("EOF while parsing character constant");
+               case EOF: {
+                       source_position_t source_position = lexer_token.source_position;
+                       source_position.linenr = start_linenr;
+                       errorf(&source_position, "EOF while parsing character constant");
                        lexer_token.type = T_ERROR;
                        return;
+               }
 
-               default:
-                       if(found_char != 0) {
-                               parse_error("more than 1 characters in character "
-                                           "constant");
-                               goto end_of_wide_char_constant;
-                       } else {
-                               found_char = c;
-                               next_char();
-                       }
+               default: {
+                       wchar_rep_t tc = (wchar_rep_t) c;
+                       obstack_grow(&symbol_obstack, &tc, sizeof(tc));
+                       next_char();
                        break;
                }
+               }
        }
 
-end_of_wide_char_constant:
-       lexer_token.type       = T_INTEGER;
-       lexer_token.v.intvalue = found_char;
-       lexer_token.datatype   = type_wchar_t;
+end_of_wide_char_constant:;
+       size_t             size   = (size_t) obstack_object_size(&symbol_obstack);
+       assert(size % sizeof(wchar_rep_t) == 0);
+       size /= sizeof(wchar_rep_t);
+
+       const wchar_rep_t *string = obstack_finish(&symbol_obstack);
+
+       lexer_token.type                = T_WIDE_CHARACTER_CONSTANT;
+       lexer_token.v.wide_string.begin = string;
+       lexer_token.v.wide_string.size  = size;
+       lexer_token.datatype            = type_wchar_t;
 }
 
+/**
+ * Parse a wide string literal and set lexer_token.
+ */
 static void parse_wide_string_literal(void)
 {
        const unsigned start_linenr = lexer_token.source_position.linenr;
@@ -848,7 +1316,7 @@ static void parse_wide_string_literal(void)
                        source_position_t source_position;
                        source_position.input_name = lexer_token.source_position.input_name;
                        source_position.linenr     = start_linenr;
-                       errorf(source_position, "string has no end");
+                       errorf(&source_position, "string has no end");
                        lexer_token.type = T_ERROR;
                        return;
                }
@@ -891,40 +1359,47 @@ end_of_string:;
        lexer_token.v.wide_string.size  = size;
 }
 
+/**
+ * Parse a character constant and set lexer_token.
+ */
 static void parse_character_constant(void)
 {
        const unsigned start_linenr = lexer_token.source_position.linenr;
 
        eat('\'');
 
-       int tc;
        while(1) {
                switch(c) {
-               case '\\':
-                       tc = parse_escape_sequence();
-                       obstack_1grow(&symbol_obstack, (char) tc);
+               case '\\': {
+                       utf32 const tc = parse_escape_sequence();
+                       if (tc >= 0x100) {
+                               warningf(&lexer_token.source_position,
+                                               "escape sequence out of range");
+                       }
+                       obstack_1grow(&symbol_obstack, tc);
                        break;
+               }
 
                MATCH_NEWLINE(
                        parse_error("newline while parsing character constant");
                        break;
                )
 
+               case '\'':
+                       next_char();
+                       goto end_of_char_constant;
+
                case EOF: {
                        source_position_t source_position;
                        source_position.input_name = lexer_token.source_position.input_name;
                        source_position.linenr     = start_linenr;
-                       errorf(source_position, "EOF while parsing character constant");
+                       errorf(&source_position, "EOF while parsing character constant");
                        lexer_token.type = T_ERROR;
                        return;
                }
 
-               case '\'':
-                       next_char();
-                       goto end_of_char_constant;
-
                default:
-                       obstack_1grow(&symbol_obstack, (char) c);
+                       grow_symbol(c);
                        next_char();
                        break;
 
@@ -935,12 +1410,15 @@ end_of_char_constant:;
        const size_t      size   = (size_t)obstack_object_size(&symbol_obstack);
        const char *const string = obstack_finish(&symbol_obstack);
 
-       lexer_token.type           = T_CHARS;
+       lexer_token.type           = T_CHARACTER_CONSTANT;
        lexer_token.v.string.begin = string;
        lexer_token.v.string.size  = size;
-       lexer_token.datatype       = type_int;
+       lexer_token.datatype       = c_mode & _CXX && size == 1 ? type_char : type_int;
 }
 
+/**
+ * Skip a multiline comment.
+ */
 static void skip_multiline_comment(void)
 {
        unsigned start_linenr = lexer_token.source_position.linenr;
@@ -950,7 +1428,10 @@ static void skip_multiline_comment(void)
                case '/':
                        next_char();
                        if (c == '*') {
-                               /* TODO: nested comment, warn here */
+                               /* nested comment, warn here */
+                               if (warning.comment) {
+                                       warningf(&lexer_token.source_position, "'/*' within comment");
+                               }
                        }
                        break;
                case '*':
@@ -967,7 +1448,7 @@ static void skip_multiline_comment(void)
                        source_position_t source_position;
                        source_position.input_name = lexer_token.source_position.input_name;
                        source_position.linenr     = start_linenr;
-                       errorf(source_position, "at end of file while looking for comment end");
+                       errorf(&source_position, "at end of file while looking for comment end");
                        return;
                }
 
@@ -978,6 +1459,9 @@ static void skip_multiline_comment(void)
        }
 }
 
+/**
+ * Skip a single line comment.
+ */
 static void skip_line_comment(void)
 {
        while(1) {
@@ -989,6 +1473,15 @@ static void skip_line_comment(void)
                case '\r':
                        return;
 
+               case '\\':
+                       next_char();
+                       if (c == '\n' || c == '\r') {
+                               if (warning.comment)
+                                       warningf(&lexer_token.source_position, "multi-line comment");
+                               return;
+                       }
+                       break;
+
                default:
                        next_char();
                        break;
@@ -996,14 +1489,21 @@ static void skip_line_comment(void)
        }
 }
 
+/** The current preprocessor token. */
 static token_t pp_token;
 
+/**
+ * Read the next preprocessor token.
+ */
 static inline void next_pp_token(void)
 {
        lexer_next_preprocessing_token();
        pp_token = lexer_token;
 }
 
+/**
+ * Eat all preprocessor tokens until newline.
+ */
 static void eat_until_newline(void)
 {
        while(pp_token.type != '\n' && pp_token.type != T_EOF) {
@@ -1011,6 +1511,9 @@ static void eat_until_newline(void)
        }
 }
 
+/**
+ * Handle the define directive.
+ */
 static void define_directive(void)
 {
        lexer_next_preprocessing_token();
@@ -1020,6 +1523,9 @@ static void define_directive(void)
        }
 }
 
+/**
+ * Handle the ifdef directive.
+ */
 static void ifdef_directive(int is_ifndef)
 {
        (void) is_ifndef;
@@ -1028,11 +1534,17 @@ static void ifdef_directive(int is_ifndef)
        //extect_newline();
 }
 
+/**
+ * Handle the endif directive.
+ */
 static void endif_directive(void)
 {
        //expect_newline();
 }
 
+/**
+ * Parse the line directive.
+ */
 static void parse_line_directive(void)
 {
        if(pp_token.type != T_INTEGER) {
@@ -1049,6 +1561,88 @@ static void parse_line_directive(void)
        eat_until_newline();
 }
 
+/**
+ * STDC pragmas.
+ */
+typedef enum stdc_pragma_kind_t {
+       STDC_UNKNOWN,
+       STDC_FP_CONTRACT,
+       STDC_FENV_ACCESS,
+       STDC_CX_LIMITED_RANGE
+} stdc_pragma_kind_t;
+
+/**
+ * STDC pragma values.
+ */
+typedef enum stdc_pragma_value_kind_t {
+       STDC_VALUE_UNKNOWN,
+       STDC_VALUE_ON,
+       STDC_VALUE_OFF,
+       STDC_VALUE_DEFAULT
+} stdc_pragma_value_kind_t;
+
+/**
+ * Parse a pragma directive.
+ */
+static void parse_pragma(void)
+{
+       bool unknown_pragma = true;
+
+       next_pp_token();
+       if (pp_token.v.symbol->pp_ID == TP_STDC) {
+               stdc_pragma_kind_t kind = STDC_UNKNOWN;
+               /* a STDC pragma */
+               if (c_mode & _C99) {
+                       next_pp_token();
+
+                       switch (pp_token.v.symbol->pp_ID) {
+                       case TP_FP_CONTRACT:
+                               kind = STDC_FP_CONTRACT;
+                               break;
+                       case TP_FENV_ACCESS:
+                               kind = STDC_FENV_ACCESS;
+                               break;
+                       case TP_CX_LIMITED_RANGE:
+                               kind = STDC_CX_LIMITED_RANGE;
+                               break;
+                       default:
+                               break;
+                       }
+                       if (kind != STDC_UNKNOWN) {
+                               stdc_pragma_value_kind_t value = STDC_VALUE_UNKNOWN;
+                               next_pp_token();
+                               switch (pp_token.v.symbol->pp_ID) {
+                               case TP_ON:
+                                       value = STDC_VALUE_ON;
+                                       break;
+                               case TP_OFF:
+                                       value = STDC_VALUE_OFF;
+                                       break;
+                               case TP_DEFAULT:
+                                       value = STDC_VALUE_DEFAULT;
+                                       break;
+                               default:
+                                       break;
+                               }
+                               if (value != STDC_VALUE_UNKNOWN) {
+                                       unknown_pragma = false;
+                               } else {
+                                       errorf(&pp_token.source_position, "bad STDC pragma argument");
+                               }
+                       }
+               }
+       } else {
+               unknown_pragma = true;
+       }
+       eat_until_newline();
+       if (unknown_pragma && warning.unknown_pragmas) {
+               warningf(&pp_token.source_position, "encountered unknown #pragma");
+       }
+}
+
+/**
+ * Parse a preprocessor non-null directive.
+ */
 static void parse_preprocessor_identifier(void)
 {
        assert(pp_token.type == T_IDENTIFIER);
@@ -1083,14 +1677,14 @@ static void parse_preprocessor_identifier(void)
                parse_error("#error directive: ");
                break;
        case TP_pragma:
-               if (warning.unknown_pragmas) {
-                       warningf(lexer_token.source_position, "encountered unknown #pragma");
-               }
-               eat_until_newline();
+               parse_pragma();
                break;
        }
 }
 
+/**
+ * Parse a preprocessor directive.
+ */
 static void parse_preprocessor_directive(void)
 {
        next_pp_token();
@@ -1102,6 +1696,9 @@ static void parse_preprocessor_directive(void)
        case T_INTEGER:
                parse_line_directive();
                break;
+       case '\n':
+               /* NULL directive, see § 6.10.7 */
+               break;
        default:
                parse_error("invalid preprocessor directive");
                eat_until_newline();
@@ -1122,7 +1719,7 @@ static void parse_preprocessor_directive(void)
 
 #define ELSE_CODE(code)                                    \
                                default:                                   \
-                                       code;                                  \
+                                       code                                   \
                                }                                          \
                        } /* end of while(1) */                        \
                        break;
@@ -1174,16 +1771,7 @@ void lexer_next_preprocessing_token(void)
 
                case '.':
                        MAYBE_PROLOG
-                               case '0':
-                               case '1':
-                               case '2':
-                               case '3':
-                               case '4':
-                               case '5':
-                               case '6':
-                               case '7':
-                               case '8':
-                               case '9':
+                               DIGITS
                                        put_back(c);
                                        c = '.';
                                        parse_number_dec();
@@ -1239,25 +1827,25 @@ void lexer_next_preprocessing_token(void)
                        ELSE('/')
                case '%':
                        MAYBE_PROLOG
-                       MAYBE('>', T_PERCENTGREATER)
+                       MAYBE('>', '}')
                        MAYBE('=', T_PERCENTEQUAL)
                                case ':':
                                        MAYBE_PROLOG
                                                case '%':
                                                        MAYBE_PROLOG
-                                                       MAYBE(':', T_PERCENTCOLONPERCENTCOLON)
+                                                       MAYBE(':', T_HASHHASH)
                                                        ELSE_CODE(
                                                                put_back(c);
                                                                c = '%';
-                                                               lexer_token.type = T_PERCENTCOLON;
+                                                               lexer_token.type = '#';
                                                                return;
                                                        )
-                                       ELSE(T_PERCENTCOLON)
+                                       ELSE('#')
                        ELSE('%')
                case '<':
                        MAYBE_PROLOG
-                       MAYBE(':', T_LESSCOLON)
-                       MAYBE('%', T_LESSPERCENT)
+                       MAYBE(':', '[')
+                       MAYBE('%', '{')
                        MAYBE('=', T_LESSEQUAL)
                                case '<':
                                        MAYBE_PROLOG
@@ -1283,7 +1871,7 @@ void lexer_next_preprocessing_token(void)
                        ELSE('|')
                case ':':
                        MAYBE_PROLOG
-                       MAYBE('>', T_COLONGREATER)
+                       MAYBE('>', ']')
                        ELSE(':')
                case '=':
                        MAYBE_PROLOG
@@ -1314,8 +1902,9 @@ void lexer_next_preprocessing_token(void)
                        return;
 
                default:
+dollar_sign:
+                       errorf(&lexer_token.source_position, "unknown character '%c' found", c);
                        next_char();
-                       errorf(lexer_token.source_position, "unknown character '%c' found\n", c);
                        lexer_token.type = T_ERROR;
                        return;
                }
@@ -1325,15 +1914,13 @@ void lexer_next_preprocessing_token(void)
 void lexer_next_token(void)
 {
        lexer_next_preprocessing_token();
-       if(lexer_token.type != '\n')
-               return;
 
+       while (lexer_token.type == '\n') {
 newline_found:
-       do {
                lexer_next_preprocessing_token();
-       } while(lexer_token.type == '\n');
+       }
 
-       if(lexer_token.type == '#') {
+       if (lexer_token.type == '#') {
                parse_preprocessor_directive();
                goto newline_found;
        }
@@ -1342,6 +1929,7 @@ newline_found:
 void init_lexer(void)
 {
        strset_init(&stringset);
+       symbol_L = symbol_table_insert("L");
 }
 
 void lexer_open_stream(FILE *stream, const char *input_name)
@@ -1350,7 +1938,6 @@ void lexer_open_stream(FILE *stream, const char *input_name)
        lexer_token.source_position.linenr     = 0;
        lexer_token.source_position.input_name = input_name;
 
-       symbol_L = symbol_table_insert("L");
        bufpos = NULL;
        bufend = NULL;
 
@@ -1359,6 +1946,26 @@ void lexer_open_stream(FILE *stream, const char *input_name)
        c = '\n';
 }
 
+void lexer_open_buffer(const char *buffer, size_t len, const char *input_name)
+{
+       input                                  = NULL;
+       lexer_token.source_position.linenr     = 0;
+       lexer_token.source_position.input_name = input_name;
+
+#if 0 // TODO
+       bufpos = buffer;
+       bufend = buffer + len;
+#else
+       (void)buffer;
+       (void)len;
+       panic("builtin lexing not done yet");
+#endif
+
+       /* place a virtual \n at the beginning so the lexer knows that we're
+        * at the beginning of a line */
+       c = '\n';
+}
+
 void exit_lexer(void)
 {
        strset_destroy(&stringset);