[PATCH v5 1/1] userdiff: extend Bash pattern to cover more shell function forms

[Moumita <dhar61595@gmail.com>]

From: Moumita Dhar <dhar61595@gmail.com>

The previous function regex required explicit matching of function
bodies using `{`, `(`, `((`, or `[[`, which caused several issues:

- It failed to capture valid functions where `{` was on the next line
  due to line continuation (`\`).
- It did not recognize functions with single  command body, such as
  `x () echo hello`.

Replacing the function body matching logic with `.*$`, ensures
that everything on the function definition line is captured.

Additionally, the word regex is refined to better recognize shell
syntax, including additional parameter expansion operators and
command-line options.

Signed-off-by: Moumita Dhar <dhar61595@gmail.com>
---
 t/t4018/bash-bashism-style-multiline-function |  4 ++
 .../bash-hunk-header-complete-line-capture    |  4 ++
 t/t4018/bash-posix-style-multiline-function   |  4 ++
 .../bash-posix-style-single-command-function  |  3 ++
 t/t4034-diff-words.sh                         |  1 +
 t/t4034/bash/expect                           | 38 +++++++++++++++++++
 t/t4034/bash/post                             | 33 ++++++++++++++++
 t/t4034/bash/pre                              | 33 ++++++++++++++++
 userdiff.c                                    | 28 ++++++++++----
 9 files changed, 140 insertions(+), 8 deletions(-)
 create mode 100644 t/t4018/bash-bashism-style-multiline-function
 create mode 100644 t/t4018/bash-hunk-header-complete-line-capture
 create mode 100644 t/t4018/bash-posix-style-multiline-function
 create mode 100644 t/t4018/bash-posix-style-single-command-function
 create mode 100644 t/t4034/bash/expect
 create mode 100644 t/t4034/bash/post
 create mode 100644 t/t4034/bash/pre

diff --git a/t/t4018/bash-bashism-style-multiline-function b/t/t4018/bash-bashism-style-multiline-function
new file mode 100644
index 0000000000..284d50dd99
--- /dev/null
+++ b/t/t4018/bash-bashism-style-multiline-function
@@ -0,0 +1,4 @@
+function RIGHT \
+{    
+    echo 'ChangeMe'
+}
diff --git a/t/t4018/bash-hunk-header-complete-line-capture b/t/t4018/bash-hunk-header-complete-line-capture
new file mode 100644
index 0000000000..818c8c5a5f
--- /dev/null
+++ b/t/t4018/bash-hunk-header-complete-line-capture
@@ -0,0 +1,4 @@
+func() { # RIGHT
+
+    ChangeMe
+}
\ No newline at end of file
diff --git a/t/t4018/bash-posix-style-multiline-function b/t/t4018/bash-posix-style-multiline-function
new file mode 100644
index 0000000000..cc8727cbcd
--- /dev/null
+++ b/t/t4018/bash-posix-style-multiline-function
@@ -0,0 +1,4 @@
+RIGHT() \
+{
+    ChangeMe
+}
diff --git a/t/t4018/bash-posix-style-single-command-function b/t/t4018/bash-posix-style-single-command-function
new file mode 100644
index 0000000000..398ae1c5d2
--- /dev/null
+++ b/t/t4018/bash-posix-style-single-command-function
@@ -0,0 +1,3 @@
+RIGHT() echo "hello"
+
+    ChangeMe
diff --git a/t/t4034-diff-words.sh b/t/t4034-diff-words.sh
index f51d3557f1..0be647c2fb 100755
--- a/t/t4034-diff-words.sh
+++ b/t/t4034-diff-words.sh
@@ -320,6 +320,7 @@ test_expect_success 'unset default driver' '
 
 test_language_driver ada
 test_language_driver bibtex
+test_language_driver bash
 test_language_driver cpp
 test_language_driver csharp
 test_language_driver css
diff --git a/t/t4034/bash/expect b/t/t4034/bash/expect
new file mode 100644
index 0000000000..17755e455f
--- /dev/null
+++ b/t/t4034/bash/expect
@@ -0,0 +1,38 @@
+<BOLD>diff --git a/pre b/post<RESET>
+<BOLD>index 09ac008..60ba6a2 100644<RESET>
+<BOLD>--- a/pre<RESET>
+<BOLD>+++ b/post<RESET>
+<CYAN>@@ -1,33 +1,33 @@<RESET>
+<RED>my_var<RESET><GREEN>new_var<RESET>=10
+x=<RED>123<RESET><GREEN>456<RESET>
+y=<RED>3.14<RESET><GREEN>2.71<RESET>
+z=<RED>.5<RESET><GREEN>.75<RESET>
+echo <RED>$USER<RESET><GREEN>$USERNAME<RESET>
+${<RED>HOME<RESET><GREEN>HOMEDIR<RESET>}
+((a<RED>+<RESET><GREEN>+=<RESET>b))
+((a<RED>*<RESET><GREEN>*=<RESET>b))
+((a<RED>/<RESET><GREEN>/=<RESET>b))
+((a<RED>%<RESET><GREEN>%=<RESET>b))
+((a<RED>|<RESET><GREEN>|=<RESET>b))
+((a<RED>^<RESET><GREEN>^=<RESET>b))
+((a<RED>=<RESET><GREEN>==<RESET>b))
+((a<RED>!<RESET><GREEN>!=<RESET>b))
+((a<RED><<RESET><GREEN><=<RESET>b))
+((a<RED>><RESET><GREEN>>=<RESET>b))
+$((a<RED><<RESET><GREEN><<<RESET>b))
+$((a<RED>><RESET><GREEN>>><RESET>b))
+$((a<RED>&<RESET><GREEN>&&<RESET>b))
+$((a<RED>|<RESET><GREEN>||<RESET>b))
+${a<RED>:<RESET><GREEN>:-<RESET>b}
+${a<RED>:<RESET><GREEN>:=<RESET>b}
+${a<RED>:<RESET><GREEN>:+<RESET>b}
+${a<RED>:<RESET><GREEN>:?<RESET>b}
+${a<RED>#<RESET><GREEN>##<RESET>*/}
+${a<RED>%<RESET><GREEN>%%<RESET>.*}
+${a<RED>^<RESET><GREEN>^^<RESET>}
+${a<RED>,<RESET><GREEN>,,<RESET>}
+${<GREEN>!<RESET>a}
+${a[<RED>*<RESET><GREEN>@<RESET>]}
+${a<RED>:2:3<RESET><GREEN>:4:6<RESET>}
+ls <RED>-a<RESET><GREEN>-x<RESET>
+ls <RED>--a<RESET><GREEN>--x<RESET>
diff --git a/t/t4034/bash/post b/t/t4034/bash/post
new file mode 100644
index 0000000000..669e218c30
--- /dev/null
+++ b/t/t4034/bash/post
@@ -0,0 +1,33 @@
+new_var=10
+x=456
+y=2.71
+z=.75
+echo $USERNAME
+${HOMEDIR}
+((a+=b))
+((a*=b))
+((a/=b))
+((a%=b))
+((a|=b))
+((a^=b))
+((a==b))
+((a!=b))
+((a<=b))
+((a>=b))
+$((a<<b))
+$((a>>b))
+$((a&&b))
+$((a||b))
+${a:-b}
+${a:=b}
+${a:+b}
+${a:?b}
+${a##*/}
+${a%%.*}
+${a^^}
+${a,,}
+${!a}
+${a[@]}
+${a:4:6}
+ls -x
+ls --x
diff --git a/t/t4034/bash/pre b/t/t4034/bash/pre
new file mode 100644
index 0000000000..ada8470bac
--- /dev/null
+++ b/t/t4034/bash/pre
@@ -0,0 +1,33 @@
+my_var=10
+x=123
+y=3.14
+z=.5
+echo $USER
+${HOME}
+((a+b))
+((a*b))
+((a/b))
+((a%b))
+((a|b))
+((a^b))
+((a=b))
+((a!b))
+((a<b))
+((a>b))
+$((a<b))
+$((a>b))
+$((a&b))
+$((a|b))
+${a:b}
+${a:b}
+${a:b}
+${a:b}
+${a#*/}
+${a%.*}
+${a^}
+${a,}
+${a}
+${a[*]}
+${a:2:3}
+ls -a
+ls --a
diff --git a/userdiff.c b/userdiff.c
index 340c4eb4f7..655c8fe0b1 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -59,20 +59,32 @@ PATTERNS("bash",
 	 "("
 	 "("
 	     /* POSIX identifier with mandatory parentheses */
-	     "[a-zA-Z_][a-zA-Z0-9_]*[ \t]*\\([ \t]*\\))"
+	     "([a-zA-Z_][a-zA-Z0-9_]*[ \t]*\\([ \t]*\\))"
 	 "|"
 	     /* Bashism identifier with optional parentheses */
-	     "(function[ \t]+[a-zA-Z_][a-zA-Z0-9_]*(([ \t]*\\([ \t]*\\))|([ \t]+))"
+	     "(function[ \t]+[a-zA-Z_][a-zA-Z0-9_]*(([ \t]*\\([ \t]*\\))|([ \t]+)))"
 	 ")"
-	 /* Optional whitespace */
-	 "[ \t]*"
-	 /* Compound command starting with `{`, `(`, `((` or `[[` */
-	 "(\\{|\\(\\(?|\\[\\[)"
+	 /* Everything after the function header is captured  */
+	 ".*$"
 	 /* End of captured text */
 	 ")",
 	 /* -- */
-	 /* Characters not in the default $IFS value */
-	 "[^ \t]+"),
+	 /* Identifiers: variable and function names */
+	  "[a-zA-Z_][a-zA-Z0-9_]*"
+	 /* Numeric constants: integers and decimals */
+	  "|[0-9]+(\\.[0-9]*)?|[-+]?\\.[0-9]+"
+	 /* Shell variables: $VAR, ${VAR} */
+	  "|\\$[a-zA-Z_][a-zA-Z0-9_]*|\\$\\{"
+	  /* Logical and comparison operators */
+	 "|\\|\\||&&|<<|>>|==|!=|<=|>="
+	 /* Assignment and arithmetic operators */
+	 "|[-+*/%&|^!=<>]=?"
+	 /* Additional parameter expansion operators */
+	 "|:?=|:-|:\\+|:\\?|:|#|##|%|%%|\\^\\^?|,|,,?|!|@|:[0-9]+(:[0-9]+)?"
+	 /* Command-line options (to avoid splitting -option) */
+	 "|--?[a-zA-Z0-9_-]+"
+	 /* Brackets and grouping symbols */
+	 "|\\(|\\)|\\{|\\}|\\[|\\]"),
 PATTERNS("bibtex",
 	 "(@[a-zA-Z]{1,}[ \t]*\\{{0,1}[ \t]*[^ \t\"@',\\#}{~%]*).*$",
 	 /* -- */
-- 
2.48.0