Indent: Allow indentation aligned with block start keyword

Add new variable `verilog_indent_block_on_keyword` that will make
indentation in block have an extra offset to align with the column where
"begin" keyword starts.

Author: vhda

doc/tags

@@ -9,6 +9,7 @@
 :VerilogReturnInstance	verilog_systemverilog.txt	/*:VerilogReturnInstance*
 b:verilog_disable_indent_lst	verilog_systemverilog.txt	/*b:verilog_disable_indent_lst*
 b:verilog_indent_assign_fix	verilog_systemverilog.txt	/*b:verilog_indent_assign_fix*
+b:verilog_indent_block_on_keyword	verilog_systemverilog.txt	/*b:verilog_indent_block_on_keyword*
 b:verilog_indent_width	verilog_systemverilog.txt	/*b:verilog_indent_width*
 b:verilog_syntax_custom	verilog_systemverilog.txt	/*b:verilog_syntax_custom*
 b:verilog_syntax_fold_lst	verilog_systemverilog.txt	/*b:verilog_syntax_fold_lst*
@@ -20,6 +21,7 @@ g:verilog_efm_level	verilog_systemverilog.txt	/*g:verilog_efm_level*
 g:verilog_efm_quickfix_clean	verilog_systemverilog.txt	/*g:verilog_efm_quickfix_clean*
 g:verilog_efm_uvm_lst	verilog_systemverilog.txt	/*g:verilog_efm_uvm_lst*
 g:verilog_indent_assign_fix	verilog_systemverilog.txt	/*g:verilog_indent_assign_fix*
+g:verilog_indent_block_on_keyword	verilog_systemverilog.txt	/*g:verilog_indent_block_on_keyword*
 g:verilog_indent_width	verilog_systemverilog.txt	/*g:verilog_indent_width*
 g:verilog_navigate_split	verilog_systemverilog.txt	/*g:verilog_navigate_split*
 g:verilog_navigate_split_close	verilog_systemverilog.txt	/*g:verilog_navigate_split_close*

doc/verilog_systemverilog.txt

@@ -384,6 +384,39 @@ Example:
     let b:verilog_indent_assign_fix = 1
 <
 
+         *b:verilog_indent_block_on_keyword* *g:verilog_indent_block_on_keyword*
+b:verilog_indent_block_on_keyword~
+g:verilog_indent_block_on_keyword~
+Default: undefined
+
+    Always indent lines following a block start on the "begin" keyword.
+    By default, the indentation script will use the indent of the line where
+    the block starts:
+>
+        case (value)
+            default : begin
+                x <= y;
+                y <= z;
+            end
+        endcase
+<
+    When this option is enabled the indentation will be offset to the start of
+    the "begin" keyword, as following:
+>
+        case (value)
+            default : begin
+                          x <= y;
+                          y <= z;
+                      end
+        endcase
+<
+
+Example:
+
+>
+    let b:verilog_indent_block_on_keyword = 1
+<
+
                    *b:verilog_disable_indent_lst* *g:verilog_disable_indent_lst*
 b:verilog_disable_indent_lst~
 g:verilog_disable_indent_lst~

indent/verilog_systemverilog.vim

@@ -126,7 +126,15 @@ function! GetVerilogSystemVerilogIndent()
     elseif s:curr_line =~ '^\s*\<endclass\>'
       return indent(s:SearchForBlockStart('\<class\>' , '', '\<endclass\>' , v:lnum, 0))
     elseif s:curr_line =~ '^\s*\<end\>'
-      return indent(s:SearchForBlockStart('\<begin\>' , '', '\<end\>'      , v:lnum, 1))
+      let l:start_lnum = s:SearchForBlockStart('\<begin\>' , '', '\<end\>'      , v:lnum, 1)
+      let l:start_indent = indent(l:start_lnum)
+      if (verilog_systemverilog#VariableExists("verilog_indent_block_on_keyword"))
+        let l:block_offset = match(getline(l:start_lnum)[l:start_indent:], 'begin')
+        call verilog_systemverilog#Verbose('Return indent to start of block keyword (offset=' . l:block_offset . ')')
+        return l:start_indent + l:block_offset
+      else
+        return l:start_indent
+      endif
     elseif s:curr_line =~ '^\s*\<endcase\>'
       return indent(s:SearchForBlockStart(s:vlog_case , '', '\<endcase\>'  , v:lnum, 0))
     endif
@@ -290,7 +298,12 @@ function! s:GetContextIndent()
 
     if l:line =~ '\<begin\>' && l:line !~ '\<begin\>.*\<end\>'
       call verilog_systemverilog#Verbose("Inside a 'begin end' block.")
-      return indent(l:lnum) + s:offset + l:open_offset
+      let l:block_offset = 0
+      if (verilog_systemverilog#VariableExists("verilog_indent_block_on_keyword"))
+        call verilog_systemverilog#Verbose("Matching start of block keyword")
+        let l:block_offset = match(l:line[indent(l:lnum):], 'begin')
+      endif
+      return indent(l:lnum) + s:offset + l:open_offset + l:block_offset
     elseif l:line =~ '^\s*\<fork\>'
       call verilog_systemverilog#Verbose("Inside a 'fork join' block.")
       return indent(l:lnum) + s:offset + l:open_offset