improved do statements and if statements

fixes #14

grammars/FortranModern.sublime-syntax

@@ -137,6 +137,8 @@ variables:
       {{entity_decl_list}}
     )
 
+  construct_name: (?xi:{{ident}} \s* (?=:)) # do/if statement label (a valid identifier followed by colon)
+  stmt_label: (?xi:\b \d+ \b) # a statement label (a number)
 
 
 
@@ -397,24 +399,81 @@ contexts:
 
 
   flow-control:
-    # do loop (with optional label and number)
+    # do_while_statement (must come before do_statement)
     - match: |
         (?xi)
         (?:^ \s*
-          (?:(\w+):\s*)? (do \s+ concurrent|do) \b
-          (\s+\d+\s+)?
-          \s*
+          (?: ({{construct_name}}) : )?         # 1 optional do statement label
+          \s* \b (do) \b                        # 2 do keyword
+          \s* ({{stmt_label}})?                 # 3 statement label with comma
+          \s* ,?                                #   optional comma
+          \s* \b (while) \b                     # 4 while keyword
+          (?= \s* \( )                          #   lookahead to expect opening parenthesis
+          # Can't use this stuff:
+          # \s* \(                                #   opening parenthesis
+          #         .*                            #   logical scalar expression
+          # \s* \)                                #   closing parenthesis
         )
+      scope: meta.do_while_statement.fortran
       captures:
-        1: entity.name.tag.do-loop-label.fortran
+        1: entity.name.tag.construct_name.fortran
         2: keyword.control.fortran
-        3: entity.name.statement-label.fortran
+        3: entity.name.statement-label.fortran constant.numeric
+        4: keyword.control.fortran
+    # do_statement
+    - match: |
+        (?xi)
+        (?:^ \s*
+          (?: ({{construct_name}}) : )?         # optional do statement label
+          \s* \b (do|do \s+ concurrent) \b      # do keyword
+          \s* ({{stmt_label}})?                 # statement label with comma
+          \s* (?:
+                ,?                              # optional comma
+                \s* ({{ident}})                 # loop variable name
+                \s* (=)                         # equals sign
+                # Can't match this stuff due to lack of regex for an expression
+                # \s* an_expr_                  # expression 1
+                # \s* ,                         # comma
+                # \s* an_expr_                  # expression 2
+                # (
+                #   \s* ,
+                #   \s* an_expr_                # expression 3
+                # )?
+              )?
+        )
+      scope: meta.do_statement.fortran
+      captures:
+        1: entity.name.tag.construct_name.fortran
+        2: keyword.control.fortran
+        3: entity.name.statement-label.fortran constant.numeric
+        4: variable.do_loop_variable.fortran
+        5: keyword.operator.fortran
+    # block_if_statement
+    - match: |
+        (?xi)
+        (?:^ \s*
+          (?: ({{construct_name}}) : )?         # 1 optional if statement label
+          \s* \b (if) \b                        # 2 if keyword
+          (?= \s* \( )                          #   lookahead to expect opening parenthesis
+          # Can't match this stuff due to lack of regex for an expression
+          # \s* \(                                #   opening parenthesis
+          #         .*                            #   logical scalar expression
+          # \s* \)                                #   closing parenthesis
+          # \s* \b (then) \b                      # 3 then keyword
+        )
+      scope: meta.block_if_statement.fortran
+      captures:
+        1: entity.name.tag.construct_name.fortran
+        2: keyword.control.fortran
+
+
+
     - match: (?xi:^ \s* (end) \s* (do) (\s+ {{ident}})? )
       captures:
         0: meta.end-statement.fortran
         1: keyword.control.fortran
         2: keyword.control.fortran
-        3: entity.name.tag.do-loop-label.fortran
+        3: entity.name.tag.construct_name.fortran
     # GOTO statement
     - match: (?xi:^ \s* (go) \s* (to) \s+ (\d+) )
       captures:
@@ -428,7 +487,6 @@ contexts:
         (?:
           \b( assign
             | to
-            | if
             | then
             | else
             | elseif
@@ -465,6 +523,7 @@ contexts:
 
 
 
+
   misc-keywords:
     # contains
     - match: (?xi:\b contains \b)