From 17b32b6bddbfc5659ea1670b2d4c00a2ca8a5812 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Mon, 4 Aug 2025 22:49:49 +0200
Subject: [PATCH] Support hexadecimal literals

---
 boot/driver.cc   |  2 +-
 boot/lexer.ll    | 65 +++++++++++++++++++++++++++++++-----------------
 source/main.elna |  6 +++++
 3 files changed, 49 insertions(+), 24 deletions(-)

diff --git a/boot/driver.cc b/boot/driver.cc
index 2443dbc..c9a8e58 100644
--- a/boot/driver.cc
+++ b/boot/driver.cc
@@ -117,7 +117,7 @@ namespace elna::boot
             }
             ++current_position;
         }
-        result.pop_back();
+        result.pop_back(); // Remove the terminating quote character.
 
         return result;
     }
diff --git a/boot/lexer.ll b/boot/lexer.ll
index 5ac68ff..4f697e6 100644
--- a/boot/lexer.ll
+++ b/boot/lexer.ll
@@ -32,6 +32,10 @@ along with GCC; see the file COPYING3.  If not see
 
 %x IN_COMMENT
 
+ID1 [A-Za-z_]
+ID2 [A-Za-z0-9_]
+HIGIT [0-9a-fA-F]
+
 %%
 %{
     this->location.step();
@@ -113,7 +117,7 @@ nil                     {
 xor                     {
                             return yy::parser::make_XOR(this->location);
                         }
-or                     {
+or                      {
                             return yy::parser::make_OR(this->location);
                         }
 \|                      {
@@ -146,43 +150,58 @@ case                    {
 of                      {
                             return yy::parser::make_OF(this->location);
                         }
-[A-Za-z_][A-Za-z0-9_]*  {
+{ID1}{ID2}*             {
                             return yy::parser::make_IDENTIFIER(yytext, this->location);
                         }
-#[A-Za-z_][A-Za-z0-9_]* {
+#{ID1}{ID2}*            {
                             return yy::parser::make_TRAIT(yytext + 1, this->location);
                         }
-[0-9]+u                 {
-                            return yy::parser::make_WORD(strtoul(yytext, NULL, 10), this->location);
-                        }
-[0-9]+                  {
-                            return yy::parser::make_INTEGER(strtol(yytext, NULL, 10), this->location);
-                        }
-[0-9]+\.[0-9]           {
-                            return yy::parser::make_FLOAT(strtof(yytext, NULL), this->location);
-                        }
-'[[:print:]]'           {
-                            if (yytext[1] == '\\' || yytext[1] == '\'')
+[[:digit:]]+u           {
+                            unsigned long result = strtoul(yytext, NULL, 10);
+
+                            if (errno == ERANGE)
                             {
                                 REJECT;
                             }
                             else
                             {
-                                return yy::parser::make_CHARACTER(std::string(yytext, 1, 1), this->location);
+                                return yy::parser::make_WORD(result, this->location);
                             }
                         }
-'\\x[0-9a-fA-F]{1,2}'   {
-                            char character = static_cast<char>(std::stoi(yytext + 3, nullptr, 16));
+[[:digit:]]+            {
+                            long result = strtol(yytext, NULL, 10);
 
-                            return yy::parser::make_CHARACTER(std::string(&character, 1), this->location);
-                        }
-'\\[0nabtfrv\\'"?]'     {
-                            char escape = escape_char(yytext[2]);
-                            if (escape == escape_invalid_char)
+                            if (errno == ERANGE)
                             {
                                 REJECT;
                             }
-                            return yy::parser::make_CHARACTER(std::string(&escape, 1), this->location);
+                            else
+                            {
+                                return yy::parser::make_INTEGER(result, this->location);
+                            }
+                        }
+0x{HIGIT}+              {
+                            unsigned long result = strtoul(yytext, NULL, 16);
+
+                            if (errno == ERANGE)
+                            {
+                                REJECT;
+                            }
+                            else
+                            {
+                                return yy::parser::make_WORD(result, this->location);
+                            }
+                        }
+[0-9]+\.[0-9]           {
+                            return yy::parser::make_FLOAT(strtof(yytext, NULL), this->location);
+                        }
+'[[:print:]]+'          {
+                            std::optional<std::string> result = escape_string(yytext);
+                            if (!result.has_value() || result.value().size() != 1)
+                            {
+                                REJECT;
+                            }
+                            return yy::parser::make_CHARACTER(result.value(), this->location);
                         }
 \"[[:print:]]*\"        {
                             std::optional<std::string> result = escape_string(yytext);
diff --git a/source/main.elna b/source/main.elna
index 0f3d001..2da63e7 100644
--- a/source/main.elna
+++ b/source/main.elna
@@ -1074,6 +1074,12 @@ begin
   return return_code
 end;
 
+proc f();
+var x: Char;
+begin
+  x := '\x4'
+end;
+
 begin
   exit(process(count, parameters))
 end.