runtime(vb): update vb indent plugin as vim9script

Include an updated vb indent script using vim9script.
Also update the runtime indent test files

Signed-off-by: Michael Soyka <mssr953@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

3 files changed, 242 insertions, 120 deletions

diff --git a/runtime/indent/testdir/vb.in b/runtime/indent/testdir/vb.in
index 1653ae6f80..cb964f792c 100644
--- a/runtime/indent/testdir/vb.in
+++ b/runtime/indent/testdir/vb.in
@@ -1,6 +1,16 @@
 ' vim: filetype=vb shiftwidth=4 expandtab
 '
 ' START_INDENT
+#Const Debug = False
+
+#If Win64 Then
+' Win64=true, Win32=true, Win16=false
+#ElseIf Win32 Then
+' Win32=true, Win16=false
+#Else
+' Win16=true
+#End If
+
 Public Type GEmployeeRecord     ' Create user-defined type. 
 ID As Integer               ' Define elements of data type. 
 Name As String * 20 
@@ -95,6 +105,9 @@ Public Sub TestMultiline (cellAddr As String, rowNbr As Long)
 Dim rng As Range
 
 Set rng = Range(cellAddr)
+
+' Line continuation is implemented as a two-character sequence-
+' whitespace followed by underscore.
 With rng
 .Cells(1,1).Value = _
 "Line 1 of multiline string; " & _
@@ -102,14 +115,25 @@ With rng
 "Line 3 of multiline string"
 End With
 
-' The following lines have whitespace after the underscore character
-' and therefore do not form a valid multiline statement.  The indent
-' script correctly treats them as four single line statements contrary
-' to the author's obvious indent.
-rng..Cells(1,1).Value = _ 
+' This code block omits the leading whitespace character and so 
+' the trailing underscore will not be treated as line continuation.
+With rng
+.Cells(1,1).Value =_
+"Line 1 of multiline string; " &_
+"Line 2 of multiline string; " &_
+"Line 3 of multiline string"
+End With
+
+' The following lines have whitespace after the underscore character.
+' This is contrary to Microsoft documentation but it is reported that
+' some Microsoft editors allow it and will still treat the statement
+' as line-continued.  
+With rng
+rng.Cells(1,1).Value = _ 
 "Line 1 of multiline string; " & _ 
 "Line 2 of multiline string; " & _ 
 "Line 3 of multiline string"
+End With
 
 End Sub
 
@@ -121,6 +145,18 @@ stmtLabel:
 
 End Sub
 
+Public Static Function TestStatic(addend As Integer)
+Dim Integer accumulator
+accumulator = accumulator + addend
+TestStatic = accumulator
+End Function
+
+Friend Function TestFriend(addend As Integer)
+Static Integer accumulator
+accumulator = accumulator + addend
+TestFriend = accumulator
+End Function
+
 Sub TestTypeKeyword()
 Type EmployeeRecord         ' Create user-defined type. 
 ID As Integer           ' Define elements of data type. 
@@ -131,4 +167,10 @@ HireDate As Date
 End Type 
 Dim varType As EmployeeRecord
 End Sub
+
+Sub TestDateLiteralAfterLineContinuation
+Dim birthday as Date
+birthday = _
+#January 1, 1901#
+End Sub
 ' END_INDENT
diff --git a/runtime/indent/testdir/vb.ok b/runtime/indent/testdir/vb.ok
index 143c688708..01a1a4c07c 100644
--- a/runtime/indent/testdir/vb.ok
+++ b/runtime/indent/testdir/vb.ok
@@ -1,6 +1,16 @@
 ' vim: filetype=vb shiftwidth=4 expandtab
 '
 ' START_INDENT
+#Const Debug = False
+
+#If Win64 Then
+' Win64=true, Win32=true, Win16=false
+#ElseIf Win32 Then
+' Win32=true, Win16=false
+#Else
+' Win16=true
+#End If
+
 Public Type GEmployeeRecord     ' Create user-defined type. 
     ID As Integer               ' Define elements of data type. 
     Name As String * 20 
@@ -95,6 +105,9 @@ Public Sub TestMultiline (cellAddr As String, rowNbr As Long)
     Dim rng As Range
 
     Set rng = Range(cellAddr)
+
+    ' Line continuation is implemented as a two-character sequence-
+    ' whitespace followed by underscore.
     With rng
         .Cells(1,1).Value = _
             "Line 1 of multiline string; " & _
@@ -102,14 +115,25 @@ Public Sub TestMultiline (cellAddr As String, rowNbr As Long)
             "Line 3 of multiline string"
     End With
 
-    ' The following lines have whitespace after the underscore character
-    ' and therefore do not form a valid multiline statement.  The indent
-    ' script correctly treats them as four single line statements contrary
-    ' to the author's obvious indent.
-    rng..Cells(1,1).Value = _ 
-    "Line 1 of multiline string; " & _ 
-    "Line 2 of multiline string; " & _ 
-    "Line 3 of multiline string"
+    ' This code block omits the leading whitespace character and so 
+    ' the trailing underscore will not be treated as line continuation.
+    With rng
+        .Cells(1,1).Value =_
+        "Line 1 of multiline string; " &_
+        "Line 2 of multiline string; " &_
+        "Line 3 of multiline string"
+    End With
+
+    ' The following lines have whitespace after the underscore character.
+    ' This is contrary to Microsoft documentation but it is reported that
+    ' some Microsoft editors allow it and will still treat the statement
+    ' as line-continued.  
+    With rng
+        rng.Cells(1,1).Value = _ 
+            "Line 1 of multiline string; " & _ 
+            "Line 2 of multiline string; " & _ 
+            "Line 3 of multiline string"
+    End With
 
 End Sub
 
@@ -121,6 +145,18 @@ stmtLabel:
 
 End Sub
 
+Public Static Function TestStatic(addend As Integer)
+    Dim Integer accumulator
+    accumulator = accumulator + addend
+    TestStatic = accumulator
+End Function
+
+Friend Function TestFriend(addend As Integer)
+    Static Integer accumulator
+    accumulator = accumulator + addend
+    TestFriend = accumulator
+End Function
+
 Sub TestTypeKeyword()
     Type EmployeeRecord         ' Create user-defined type. 
         ID As Integer           ' Define elements of data type. 
@@ -131,4 +167,10 @@ Sub TestTypeKeyword()
     End Type 
     Dim varType As EmployeeRecord
 End Sub
+
+Sub TestDateLiteralAfterLineContinuation
+    Dim birthday as Date
+    birthday = _
+        #January 1, 1901#
+End Sub
 ' END_INDENT
diff --git a/runtime/indent/vb.vim b/runtime/indent/vb.vim
index bc7142f428..a2a8185363 100644
--- a/runtime/indent/vb.vim
+++ b/runtime/indent/vb.vim
@@ -1,155 +1,193 @@
-" Vim indent file
-" Language:	VisualBasic (ft=vb) / Basic (ft=basic) / SaxBasic (ft=vb)
-" Author:	Johannes Zellner <johannes@zellner.org>
-" Maintainer:	Michael Soyka (mssr953@gmail.com)
-" Last Change:	Fri, 18 Jun 2004 07:22:42 CEST
-"		Small update 2010 Jul 28 by Maxim Kim
-"		2022/12/15: add support for multiline statements.
-"		2022/12/21: move VbGetIndent from global to script-local scope
-"		2022/12/26: recognize "Type" keyword
+vim9script
+
+# Vim indent file
+# Language:	VisualBasic (ft=vb) / Basic (ft=basic) / SaxBasic (ft=vb)
+# Author:	Johannes Zellner <johannes@zellner.org>
+# Maintainer:	Michael Soyka (mssr953@gmail.com)
+# Contributors: Doug Kearns (dougkearns@gmail.com)
+# Last Change:	Fri, 18 Jun 2004 07:22:42 CEST
+#		Small update 2010 Jul 28 by Maxim Kim
+#		2022/12/15: add support for multiline statements.
+#		2022/12/21: move VbGetIndent from global to script-local scope
+#		2022/12/26: recognize "Type" keyword
+#		2023/07/13: correct/extend line continuation pattern (Doug Kearns)
+#		2023/07/14: add more keywords; various optimizations (Doug Kearns)
+#		2023/07/20: convert to Vim9 script
+#		2023/07/23: improve detection of preproc directives (Doug Kearns)
 
 if exists("b:did_indent")
     finish
 endif
-let b:did_indent = 1
+b:did_indent = v:true
 
 setlocal autoindent
-setlocal indentexpr=s:VbGetIndent(v:lnum)
+setlocal indentexpr=VbGetIndent()
 setlocal indentkeys&
 setlocal indentkeys+==~else,=~elseif,=~end,=~wend,=~case,=~next,=~select,=~loop
 
-let b:undo_indent = "set ai< indentexpr< indentkeys<"
+b:undo_indent = "setlocal autoindent< indentexpr< indentkeys<"
 
-" Only define the function once.
-if exists("*s:VbGetIndent")
+# Only define the function once.
+if exists("*VbGetIndent")
     finish
 endif
 
-function s:VbGetIndent(lnum)
-    let this_lnum = a:lnum
-    let this_line = getline(this_lnum)
+# These regular expressions identify statement labels and preprocessor
+# directives.
+#
+const RE_LABEL: string = '^\s*\k\+:\s*$'
+const RE_PREPROC: string =
+    '^\s*#\%(const\|if\|elseif\|else\|end\|region\|enable\|disable\)\>'
+
+# Microsoft documentation states that line continuation is indicated by a
+# two-character sequence at end-of-line: a space character followed by an
+# underscore.  Nonetheless, it has been reported that additional
+# whitespace after the underscore is also allowed.  We will support both.
+# However, VB 16.0 also permits a comment after the underscore which,
+# for simplicity, we do not support.
+#
+const RE_LINE_CONTINUATION: string = '\s_\s*$'
+
+# The following regular expressions are used to increase the indent
+# after statements that open a new scope.
+#
+const RE_INCR_INDENT_1: string =
+    '^\s*\%(begin\|select\|case\|default\|if\|else\|elseif\|do\|for\|while\|with\)\>'
+const RE_INCR_INDENT_2: string =
+    '^\s*\%(\%(private\|public\|friend\)\s\+\)\=\%(static\s\+\)\=\%(function\|sub\|property\)\>'
+const RE_INCR_INDENT_3: string =
+    '^\s*\%(\%(private\|public\)\s\+\)\=\%(enum\|type\)\>'
 
-    " labels and preprocessor get zero indent immediately
-    let LABELS_OR_PREPROC = '^\s*\(\<\k\+\>:\s*$\|#.*\)'
-    if this_line =~? LABELS_OR_PREPROC
-	return 0
+def VbGetIndent(): number
+    var this_lnum: number = v:lnum
+    var this_line: string = getline(this_lnum)
+    var this_indent: number = 0
+
+    # labels and preprocessor statements get zero indent immediately
+    if (this_line =~? RE_LABEL) || (this_line =~? RE_PREPROC)
+	return this_indent
     endif
-    
-    " Get the current value of "shiftwidth"
-    let bShiftwidth = shiftwidth()
 
-    " Find a non-blank line above the current line.
-    " Skip over labels and preprocessor directives.
-    let lnum = this_lnum
+    # Get the current value of 'shiftwidth'
+    const SHIFTWIDTH: number = shiftwidth()
+
+    # Find a non-blank line above the current line.
+    # Skip over labels and preprocessor directives.
+    var lnum: number = this_lnum
+    var previous_line: string
     while lnum > 0
-	let lnum = prevnonblank(lnum - 1)
-	let previous_line = getline(lnum)
-	if previous_line !~? LABELS_OR_PREPROC
+	lnum = prevnonblank(lnum - 1)
+	previous_line = getline(lnum)
+	if (previous_line !~? RE_LABEL) || (previous_line !~? RE_PREPROC)
 	    break
 	endif
     endwhile
 
-    " Hit the start of the file, use zero indent.
+    # Hit the start of the file, use zero indent.
     if lnum == 0
-	return 0
+	return this_indent
     endif
 
-    " Variable "previous_line" now contains the text in buffer line "lnum".
-
-    " Multi-line statements have the underscore character at end-of-line:
-    "
-    "    object.method(arguments, _
-    "                  arguments, _
-    "                  arguments)
-    "
-    " and require extra logic to determine the correct indentation.
-    "
-    " Case 1: Line "lnum" is the first line of a multiline statement.
-    "         Line "lnum" will have a trailing underscore character
-    "         but the preceding non-blank line does not.
-    "         Line "this_lnum" will be indented relative to "lnum".
-    "
-    " Case 2: Line "lnum" is the last line of a multiline statement.
-    "         Line "lnum" will not have a trailing underscore character
-    "         but the preceding non-blank line will.
-    "         Line "this_lnum" will have the same indentation as the starting
-    "         line of the multiline statement.
-    "
-    " Case 3: Line "lnum" is neither the first nor last line.  
-    "         Lines "lnum" and "lnum-1" will have a trailing underscore
-    "         character.
-    "         Line "this_lnum" will have the same indentation as the preceding
-    "         line.
-    "
-    " No matter which case it is, the starting line of the statement must be
-    " found.  It will be assumed that multiline statements cannot have
-    " intermingled comments, statement labels, preprocessor directives or
-    " blank lines.
-    "
-    let lnum_is_continued = (previous_line =~ '_$')
+    # Variable "previous_line" now contains the text in buffer line "lnum".
+
+    # Multi-line statements have the underscore character at end-of-line:
+    #
+    #    object.method(arguments, _
+    #                  arguments, _
+    #                  arguments)
+    #
+    # and require extra logic to determine the correct indentation.
+    #
+    # Case 1: Line "lnum" is the first line of a multiline statement.
+    #         Line "lnum" will have a trailing underscore character
+    #         but the preceding non-blank line does not.
+    #         Line "this_lnum" will be indented relative to "lnum".
+    #
+    # Case 2: Line "lnum" is the last line of a multiline statement.
+    #         Line "lnum" will not have a trailing underscore character
+    #         but the preceding non-blank line will.
+    #         Line "this_lnum" will have the same indentation as the starting
+    #         line of the multiline statement.
+    #
+    # Case 3: Line "lnum" is neither the first nor last line.
+    #         Lines "lnum" and "lnum-1" will have a trailing underscore
+    #         character.
+    #         Line "this_lnum" will have the same indentation as the preceding
+    #         line.
+    #
+    # No matter which case it is, the starting line of the statement must be
+    # found.  It will be assumed that multiline statements cannot have
+    # intermingled comments, statement labels, preprocessor directives or
+    # blank lines.
+    #
+    var lnum_is_continued: bool = (previous_line =~? RE_LINE_CONTINUATION)
+    var before_lnum: number
+    var before_previous_line: string
     if lnum > 1
-	let before_lnum = prevnonblank(lnum-1)
-	let before_previous_line = getline(before_lnum)
+	before_lnum = prevnonblank(lnum - 1)
+	before_previous_line = getline(before_lnum)
     else
-	let before_lnum = 0
-	let before_previous_line = ""
+	before_lnum = 0
+	before_previous_line = ""
     endif
 
-    if before_previous_line !~ '_$'
-	" Variable "previous_line" contains the start of a statement.
-	"
-	let ind = indent(lnum)
+    if before_previous_line !~? RE_LINE_CONTINUATION
+	# Variable "previous_line" contains the start of a statement.
+	#
+	this_indent = indent(lnum)
 	if lnum_is_continued
-	    let ind += bShiftwidth
+	    this_indent += SHIFTWIDTH
 	endif
     elseif ! lnum_is_continued
-	" Line "lnum" contains the last line of a multiline statement.
-        " Need to find where this multiline statement begins
-	"
+	# Line "lnum" contains the last line of a multiline statement.
+        # Need to find where this multiline statement begins
+	#
 	while before_lnum > 0
-	    let before_lnum -= 1
-	    if getline(before_lnum) !~ '_$'
-		let before_lnum += 1
+	    before_lnum -= 1
+	    if getline(before_lnum) !~? RE_LINE_CONTINUATION
+		before_lnum += 1
 		break
 	    endif
 	endwhile
 	if before_lnum == 0
-	    let before_lnum = 1
+	    before_lnum = 1
 	endif
-	let previous_line = getline(before_lnum)
-	let ind = indent(before_lnum)
+	previous_line = getline(before_lnum)
+	this_indent = indent(before_lnum)
     else
-	" Line "lnum" is not the first or last line of a multiline statement.
-	"
-	let ind = indent(lnum)
+	# Line "lnum" is not the first or last line of a multiline statement.
+	#
+	this_indent = indent(lnum)
     endif
 
-    " Add
-    if previous_line =~? '^\s*\<\(begin\|\%(\%(private\|public\|friend\)\s\+\)\=\%(function\|sub\|property\|enum\|type\)\|select\|case\|default\|if\|else\|elseif\|do\|for\|while\|with\)\>'
-	let ind = ind + bShiftwidth
+    # Increment indent
+    if (previous_line =~? RE_INCR_INDENT_1) ||
+       (previous_line =~? RE_INCR_INDENT_2) ||
+       (previous_line =~? RE_INCR_INDENT_3)
+	this_indent += SHIFTWIDTH
     endif
 
-    " Subtract
-    if this_line =~? '^\s*\<end\>\s\+\<select\>'
-	if previous_line !~? '^\s*\<select\>'
-	    let ind = ind - 2 * bShiftwidth
+    # Decrement indent
+    if this_line =~? '^\s*end\s\+select\>'
+	if previous_line !~? '^\s*select\>'
+	    this_indent -= 2 * SHIFTWIDTH
 	else
-	    " this case is for an empty 'select' -- 'end select'
-	    " (w/o any case statements) like:
-	    "
-	    " select case readwrite
-	    " end select
-	    let ind = ind - bShiftwidth
+	    # this case is for an empty 'select' -- 'end select'
+	    # (w/o any case statements) like:
+	    #
+	    # select case readwrite
+	    # end select
+	    this_indent -= SHIFTWIDTH
 	endif
-    elseif this_line =~? '^\s*\<\(end\|else\|elseif\|until\|loop\|next\|wend\)\>'
-	let ind = ind - bShiftwidth
-    elseif this_line =~? '^\s*\<\(case\|default\)\>'
-	if previous_line !~? '^\s*\<select\>'
-	    let ind = ind - bShiftwidth
+    elseif this_line =~? '^\s*\%(end\|else\|elseif\|until\|loop\|next\|wend\)\>'
+	this_indent -= SHIFTWIDTH
+    elseif this_line =~? '^\s*\%(case\|default\)\>'
+	if previous_line !~? '^\s*select\>'
+	    this_indent -= SHIFTWIDTH
 	endif
     endif
 
-    return ind
-endfunction
+    return this_indent
+enddef
 
-" vim:sw=4
+# vim:sw=4