tweaks: fold some regexes together, and trim or improve some comments

Also, trim some whitespace and group one rule better.

Also, fix a stray closing parenthesis in the JSON syntax,
and add the missing slash to the possible escaped characters.
(Reference: https://www.json.org/json-en.html.)

Also, improve the ending of multiline strings in the Rust syntax.

syntax/asm.nanorc

@@ -11,8 +11,8 @@ color brightyellow "\.(ascii|asciz|byte|double|float|hword|int|long|short|single
 color brightred "^[[:blank:]]*[.0-9A-Za-z_]*:"
 color brightcyan "^[[:blank:]]*#[[:blank:]]*(define|undef|include|ifn?def|endif|elif|else|if|warning|error)"
 
-# Strings.
-color brightyellow "<[^= 	]*>|"([^"\]|\\.)*""
+# Strings and names of included files.
+color brightyellow ""([^"\]|\\.)*"|<[^= 	]*>"
 
 # Comments.
 color brightblue "//.*"

syntax/c.nanorc

@@ -28,8 +28,7 @@ color brightmagenta "'([^'\]|\\(["'\abfnrtv]|x[0-9A-Fa-f]{1,2}|[0-3]?[0-7]{1,2})
 # GCC builtins.
 color cyan "__attribute__[[:blank:]]*\(\([^)]*\)\)" "__(aligned|asm|builtin|hidden|inline|packed|restrict|section|typeof|weak)__"
 
-# Strings.  (In general you will want your strings and comments to come last,
-# because highlighting rules are applied in the order they are read in.)
+# Strings and names of included files.
 color brightyellow ""([^"]|\\")*"" "#[[:blank:]]*include[[:blank:]]*<[^>]+>"
 
 # Preprocessor directives.

syntax/changelog.nanorc

@@ -13,13 +13,13 @@ color red "^(19|20)[0-9-]{8}"
 color yellow "<[^>]*@[^>]*>"
 
 # Command-line options.
-color cyan "[[:blank:]]-[a-zA-Z\$]" "--[8a-z-]+"
+color cyan "[[:blank:]]-[a-zA-Z\$]|--[8a-z-]+"
 # Bug and patch numbers.
-color cyan "(BZ|bug|patch)[ ]#[0-9]+" "PR [[:alnum:]]+/[0-9]+"
+color cyan "(BZ|bug|patch)[ ]#[0-9]+|PR [[:alnum:]]+/[0-9]+"
 # Probable constants, for variety.
 color brightred "\<[A-Z_][0-9A-Z_]+\>"
 # Key sequences.
-color brightblue "\^[A-Z^\]" "\<M-." "\<F1?[0-9]" "(\^|M-)Space"
+color brightblue "\^[A-Z^\]|\<M-.|\<F1?[0-9]|(\^|M-)Space"
 
 # Changed files.
 color magenta start="^(	| {8})\* " end="(:( |$)|^$)"

syntax/cmake.nanorc

@@ -15,5 +15,8 @@ icolor brightred "^[[:blank:]]*((end)?(function|macro)|return)"
 icolor cyan start="\$(ENV)?\{" end="\}"
 color magenta "\<(APPLE|UNIX|WIN32|CYGWIN|BORLAND|MINGW|MSVC(_IDE|60|71|80|90)?)\>"
 
+# Comments.
 color brightblue "(^|[[:blank:]])#.*"
+
+# Trailing whitespace.
 color ,green "[[:space:]]+$"

syntax/extra/ada.nanorc

@@ -30,7 +30,7 @@ color cyan "'[[:alnum:]]+"
 color green "\<[0-9][0-9A-Fa-f_#.+-]*"
 
 # Characters / Strings
-color red "'.'" ""[^"]*""
+color red "'.'|"[^"]*""
 
 # Comments
 color brightblue "--.*"

syntax/go.nanorc

@@ -26,6 +26,7 @@ color magenta "\<(break|continue|fallthrough|goto|return)\>"
 color brightcyan "\<(package|import)\>"
 
 # Literals.
+color red "\<(true|false|nil|iota|_)\>"
 color red "\<([1-9][0-9]*|0[0-7]*|0[xX][0-9A-Fa-f]+)\>"
 color red "\<[0-9]+\.[0-9]*([eE][+-]?[0-9]+)?i?\>"
 color red "\<[0-9]+[eE][+-]?[0-9]+i?\>"
@@ -33,7 +34,6 @@ color red "\B\.[0-9]+([eE][+-]?[0-9]+)?i?\>"
 color red "\<[0-9]+i\>"
 
 # Strings and characters; slightly fuzzy.
-color red "\<(true|false|nil|iota|_)\>"
 color red ""([^"\]|\\.)*"|'([^'\]|\\.)+'"
 color red start=""([^"\]|\\.)*\\[[:blank:]]*$" end="^([^"\]|\\.)*""
 

syntax/guile.nanorc

@@ -11,8 +11,7 @@ color brightcyan "\<define(-macro|-module|-public|-syntax)?\>"
 # Quoted symbols
 color brightyellow "'\<(\w|-)+\>"
 # Chars
-color brightmagenta "#\\."
-color brightmagenta "#\\\w+\>"
+color brightmagenta "#\\(.|\w+)"
 # Booleans
 color brightred "(#t|#f)\>"
 # Keywords

syntax/json.nanorc

@@ -14,7 +14,7 @@ color brightmagenta "".+""
 # Hex numbers (used as value).
 color green ":[[:blank:]]*"#[0-9abcdefABCDEF]+""
 # Escapes.
-color green "\\\\" "\\"" "\\[bfnrt]" "\\u[0-9abcdefABCDEF]{4})"
+color green "\\["\/bfnrt]" "\\u[0-9abcdefABCDEF]{4}"
 # Special words.
 color green "\<(true|false|null)\>"
 

syntax/nftables.nanorc

@@ -25,8 +25,10 @@ color cyan "(^|[[:blank:]])#.*"
 # Trailing whitespace
 color ,green "[[:space:]]+$"
 
-# Strings and others
+# Strings
 color yellow ""([^"\]|\\.)*"|'([^'\]|\\.)*'"
+
+# Syntactic symbols
 color green "[][{}():;|`$<>!=&\]"
 
 # Basic variable names

syntax/objc.nanorc

@@ -4,7 +4,7 @@ syntax m "\.m$"
 magic "Objective-C source"
 comment "//"
 
-# Stuffs,
+# Stuffs.
 color brightwhite "\<[A-Z_][0-9A-Z_]+\>"
 color green "\<(float|double|BOOL|bool|char|int|short|long|id|sizeof|enum|void|static|const|struct|union|typedef|extern|(un)?signed|inline)\>"
 color green "\<[[:alpha:]_][[:alnum:]_]*_t\>"
@@ -24,7 +24,7 @@ color magenta "[[:alnum:]]*:"
 color white "\[[^][:blank:]]*\]"
 
 # Strings.
-color brightblack "'([^'\]|(\\["'abfnrtv\]))'" "'\\(([0-3]?[0-7]{1,2}))'" "'\\x[0-9A-Fa-f]{1,2}'"
+color brightblack "'([^'\]|\\(["'\abfnrtv]|x[0-9A-Fa-f]{1,2}|[0-3]?[0-7]{1,2}))'"
 color brightblack "<[^= 	]*>|"([^"\]|\\.)*""
 color brightblue "@"([^"\]|\\.)*""
 

syntax/ocaml.nanorc

@@ -26,5 +26,5 @@ color green "\<(include|inherit|initializer)\>"
 color yellow "\<(new|ref|mutable|lazy|assert|raise)\>"
 # Comments:
 color white start="\(\*" end="\*\)"
-# Strings: (no multiline handling yet)
-color brightblack ""[^\"]*""
+# Strings:
+color brightblack ""[^"\]*""

syntax/rust.nanorc

@@ -23,8 +23,8 @@ color magenta "[A-Z][A-Za-z0-9]+"
 
 # Strings
 color green ""([^"]|\\")*""
-color green start=""([^"]|\\")*\\$" end=".*""
-## NOTE: This isn't accurate, but matching "#{0,} for the end of the string is too liberal.
+color green start=""([^"]|\\")*\\$" end="(^|.*[^\])""
+## Inaccurate, but it's not possible to balance the number of hashes.
 color green start="r#+"" end=""#+"
 
 # Comments

syntax/sh.nanorc

@@ -18,7 +18,7 @@ color green "[][{}():;|`$<>!=&\]"
 color green "-(eq|ne|gt|lt|ge|le|ef|ot|nt)\>"
 
 # Short and long options.
-color brightmagenta "[[:blank:]]-[A-Za-z]\>" "[[:blank:]]--[A-Za-z-]+\>"
+color brightmagenta "[[:blank:]](-[A-Za-z]|--\<[A-Za-z-]+)\>"
 
 # Common commands.
 color brightblue "\<(awk|cat|cd|ch(grp|mod|own)|cp|cut|echo|env|grep|head|install|ln|make|mkdir|mv|popd|printf|pushd|rm|rmdir|sed|set|sort|tail|tar|touch|umask|unset)\>"