implement the first homework assignment (#8)

* Rust syntax highlighter: add incomplete implementation of a scanner for the Rust programming language

* Rust syntax highlighter: fix some issues with unrecognized rules caused by unescaped literals

* Rust syntax highlighter: refactor the definitions section, fixing some escaping-related style issues

* Rust syntax highlighter: refactor the definitions and rules sections, abstracting out some hardcoded patterns

* Rust syntax highlighter: refactor, reordering the definitions, rules and CSS class definitions

* Rust syntax highlighter: refactor, fixing some style issues with the C code

* Rust syntax highlighter: refactor the code section, fixing some HTML- and CSS-related issues

* Rust syntax highlighter: drop the document title from the output as it is wrongly hardcoded

* Rust syntax highlighter: add gitignore

* Rust syntax highlighter: add C source of generated scanner

* Rust syntax highlighter: add example Rust program

1 files changed, 115 insertions, 0 deletions

diff --git a/homework/81030/rust2html.flex b/homework/81030/rust2html.flex
new file mode 100644
index 0000000..6684d82
--- /dev/null
+++ b/homework/81030/rust2html.flex
@@ -0,0 +1,115 @@
+/* scanner for the Rust programming language */
+
+%{
+#define YY_NO_UNISTD_H
+%}
+
+NONEOL_CHAR        [^\n]
+DEC_DIGIT          0|{NONZERO_DEC_DIGIT}
+NONZERO_DEC_DIGIT  [1-9]
+OCT_DIGIT          [0-7]
+HEX_DIGIT          {DEC_DIGIT}|[a-fA-F]
+
+IDENTIFIER             {IDENTIFIER_FIRST_CHAR}({DEC_DIGIT}|{IDENTIFIER_FIRST_CHAR})*
+IDENTIFIER_FIRST_CHAR  [A-Za-z_]
+
+COMMENT        {BLOCK_COMMENT}|{LINE_COMMENT}
+BLOCK_COMMENT  "/*".*"*/"
+LINE_COMMENT   "//"{NONEOL_CHAR}*
+
+KEYWORD  _|abstract|alignof|as|become|box|break|const|continue|crate|do|else|enum|extern|false|final|fn|for|if|impl|in|let|loop|macro|match|mod|move|mut|offsetof|override|priv|proc|pub|pure|ref|return|Self|self|sizeof|static|struct|super|trait|true|type|typeof|unsafe|unsized|use|virtual|where|while|yield
+
+ESCAPE          {COMMON_ESCAPE}|{UNICODE_ESCAPE}
+COMMON_ESCAPE   \\|n|r|t|0|x{HEX_DIGIT}{2}
+UNICODE_ESCAPE  "u{"{HEX_DIGIT}{6}"}"
+
+CHAR_LITERAL         '{CHAR_BODY}'
+CHAR_BODY            [^']|(\\('|{ESCAPE}))
+STRING_LITERAL       \"{STRING_BODY}*\"
+STRING_BODY          [^\"]|(\\(\"|{ESCAPE}))
+BYTE_CHAR_LITERAL    b'{BYTE_CHAR_BODY}'
+BYTE_CHAR_BODY       [^']|(\\('|{COMMON_ESCAPE}))
+BYTE_STRING_LITERAL  b\"{BYTE_STRING_BODY}*\"
+BYTE_STRING_BODY     [^\"]|(\\(\"|{ESCAPE}))
+
+NUMBER_LITERAL     {NONZERO_DEC_DIGIT}{DEC_DIGIT}*{FLOAT_SUFFIX}?|(0{DEC_DIGIT_LITERAL}*{FLOAT_SUFFIX}?|b[10_]+|o{OCT_DIGIT_LITERAL}+|x{HEX_DIGIT_LITERAL}+)
+FLOAT_SUFFIX       {EXPONENT}|"."{DEC_DIGIT_LITERAL}+{EXPONENT}?
+EXPONENT           [Ee][-+]?{DEC_DIGIT_LITERAL}+
+DEC_DIGIT_LITERAL  {DEC_DIGIT}|_
+HEX_DIGIT_LITERAL  {HEX_DIGIT}|_
+OCT_DIGIT_LITERAL  {OCT_DIGIT}|_
+
+SYMBOL  "::"|"->"|"#"|"["|"]"|"("|")"|"{"|"}"|","|";"
+
+%%
+
+{SYMBOL} {
+    printf("<span class=\"symbol\">%s</span>", yytext);
+}
+
+{KEYWORD} {
+    printf("<span class=\"keyword\">%s</span>", yytext);
+}
+
+{NUMBER_LITERAL} {
+    printf("<span class=\"number\">%s</span>", yytext);
+}
+
+{IDENTIFIER} {
+    printf("<span class=\"identifier\">%s</span>", yytext);
+}
+
+{CHAR_LITERAL}|{STRING_LITERAL}|{BYTE_CHAR_LITERAL}|{BYTE_STRING_LITERAL} {
+    printf("<span class=\"string\">%s</span>", yytext);
+}
+
+{COMMENT} {
+    printf("<span class=\"comment\">%s</span>", yytext);
+}
+
+. {
+    printf("%s", yytext);  /* echo the rest */
+}
+
+%%
+
+int yywrap() {
+    return 1;
+}
+
+int main(int argc, const char* argv[]) {
+    yyin = argc > 1 ? fopen(argv[1], "r") : stdin;
+
+    puts(
+        "<!DOCTYPE html>"
+        "<html>"
+        "<head>"
+        "    <style>"
+        "        .comment {"
+        "            color: gray;"
+        "        }"
+        "        .keyword {"
+        "            color: red;"
+        "        }"
+        "        .string {"
+        "            color: green;"
+        "        }"
+        "        .number {"
+        "            color: blue;"
+        "        }"
+        "        .symbol {"
+        "            font-weight: bold;"
+        "        }"
+        "    </style>"
+        "</head>"
+        "<body>"
+        "    <pre class=\"code\">"
+    );
+    yylex();
+    puts(
+        "    </pre>"
+        "</body>"
+        "</html>");
+
+    return 0;
+}