handle HTML comments [#22 - done]

Signed-off-by: George Lemon <georgelemon@protonmail.com>

Author: georgelemon

src/tim/engine/lexer.nim

@@ -42,7 +42,7 @@ type
     tkContinueCmd = "continue",
     tkIdentVar, tkIdentVarSafe,
     tkStatic, tkEcho = "echo",
-    tkComment, tkDoc, tkNil = "nil",
+    tkComment, tkDoc, tkHtmlComment, tkNil = "nil",
     tkUnknown
 
   TokenTuple* = tuple
@@ -351,7 +351,25 @@ proc nextToken*(lex: var Lexer): TokenTuple =
       lex.advance()
       result = initToken(lex, tkGt, line, col, pos, wsno)
   of '<':
-    if lex.peek() == '=':
+    if lex.peek() == '!' and lex.peek(2) == '-' and lex.peek(3) == '-':
+      # HTML comment <!-- ... -->
+      lex.advance() # <
+      lex.advance() # !
+      lex.advance() # -
+      lex.advance() # -
+      lex.strbuf.setLen(0)
+      while true:
+        if lex.current == '-' and lex.peek() == '-' and lex.peek(2) == '>':
+          lex.advance() # -
+          lex.advance() # -
+          lex.advance() # >
+          break
+        if lex.current == '\0':
+          lex.error("EOF reached before closing --> for HTML comment")
+        lex.strbuf.add(lex.current)
+        lex.advance()
+      result = initToken(lex, tkHtmlComment, move lex.strbuf, line, col, pos, wsno)
+    elif lex.peek() == '=':
       lex.advance()
       lex.advance()
       result = initToken(lex, tkLte, "<=", line, col, pos, wsno)

src/tim/engine/parser.nim

@@ -660,6 +660,11 @@ prefixHandle parseRawHtml:
   result.rawHtml =move output
   walk p
 
+prefixHandle parseHtmlComment:
+  result = ast.newNode(nkRawHtml)
+  result.rawHtml = "<!-- " & strip(p.curr.value) & " -->"
+  walk p
+
 #
 # Identifier & Variable Definitions
 #
@@ -1174,6 +1179,7 @@ proc getPrefixFn(p: var Parser, minPrec: int): PrefixFunction =
     of tkSnippetJs: parseJavaScript
     of tkSnippetCSS: parseCSS
     of tkSnippetHtml: parseRawHtml
+    of tkHtmlComment: parseHtmlComment
     of tkViewLoader: parseViewPlaceholder
     of tkClient: parseClientBlock
     else: nil
@@ -1309,6 +1315,7 @@ prefixHandle parseStmt:
     of tkSnippetJs: parseJavaScript
     of tkSnippetCSS: parseCSS
     of tkSnippetHtml: parseRawHtml
+    of tkHtmlComment: parseHtmlComment
     of tkViewLoader: parseViewPlaceholder
     of tkClient: parseClientBlock
     else: parseExpression

tests/test1.nim

@@ -1,5 +1,5 @@
 import std/[unittest, os, xmltree, strtabs,
-        sequtils, json, options, htmlparser]
+        sequtils, json, options, htmlparser, strutils]
 
 include ../src/tim/engine/transformers
 import pkg/vancode/interpreter/[ast, codegen, chunk, sym, vm, value, resolver]
@@ -110,3 +110,12 @@ p: "This will cause an error: " & $this["undefinedKey"]
         # this is not a code generation error, but a runtime error due  to
         # accessing an undefined key in the JSON storage, so a KeyError is expected
         assert e.msg == "key not found: undefinedKey"
+
+    test "html comments":
+      let samplecode = """
+div.container
+  <!-- This is an HTML comment -->
+  p: "Hello"
+"""
+      let html = toHtml("test8", samplecode)
+      doAssert "<!-- This is an HTML comment -->" in html