From 6d138a1181b4a6b5d9b25eb98871e789db060f5b Mon Sep 17 00:00:00 2001
From: George Lemon <georgelemon@protonmail.com>
Date: Wed, 6 Mar 2024 05:52:29 +0200
Subject: [PATCH] Add IndexRange `[0..^2]`

Signed-off-by: George Lemon <georgelemon@protonmail.com>
---
 src/tim/engine/ast.nim            |  8 +++--
 src/tim/engine/compilers/html.nim | 15 ++++++++-
 src/tim/engine/parser.nim         | 56 +++++++++++++++++++++----------
 src/tim/engine/tokens.nim         |  1 +
 4 files changed, 59 insertions(+), 21 deletions(-)

diff --git a/src/tim/engine/ast.nim b/src/tim/engine/ast.nim
index 5129103..82b133c 100755
--- a/src/tim/engine/ast.nim
+++ b/src/tim/engine/ast.nim
@@ -37,8 +37,9 @@ type
     ntIdent = "Identifier"
     ntCall = "FunctionCall"
     ntIdentPair
-    ntDotExpr
-    ntBracketExpr
+    ntDotExpr = "DotExpression"
+    ntBracketExpr = "BracketExpression"
+    ntIndexRange = "IndexRange"
     ntConditionStmt = "ConditionStatement"
     ntLoopStmt = "LoopStmt"
     ntViewLoader = "ViewLoader"
@@ -153,6 +154,9 @@ type
     of ntBracketExpr:
       bracketStorageType*: StorageType
       bracketLHS*, bracketIndex*: Node
+    of ntIndexRange:
+      rangeNodes*: array[2, Node]
+      rangeLastIndex*: bool # from end to start using ^ circumflex accent
     of ntLitFunction:
       fnIdent*: string
       fnParams*: OrderedTable[string, FnParam]
diff --git a/src/tim/engine/compilers/html.nim b/src/tim/engine/compilers/html.nim
index 435b230..62459b9 100755
--- a/src/tim/engine/compilers/html.nim
+++ b/src/tim/engine/compilers/html.nim
@@ -307,6 +307,19 @@ proc walkAccessorStorage(c: var HtmlCompiler,
         result = lhs.arrayItems[rhs.iVal]
       except Defect:
         compileErrorWithArgs(indexDefect, lhs.meta, [$(rhs.iVal), "0.." & $(lhs.arrayItems.high)])
+    of ntIndexRange:
+      let l = rhs.rangeNodes[0].iVal
+      let r = rhs.rangeNodes[1].iVal
+      try:
+        result = ast.newNode(ntLitArray)
+        result.meta = lhs.meta
+        case rhs.rangeLastIndex
+        of false:
+          result.arrayItems = lhs.arrayItems[l..r]
+        of true:
+          result.arrayItems = lhs.arrayItems[l..^r]
+      except Defect:
+        compileErrorWithArgs(indexDefect, lhs.meta, ["", "0.." & $(lhs.arrayItems.high)])
     else: compileErrorWithArgs(invalidAccessorStorage, rhs.meta, [rhs.toString, $lhs.nt])
   else: discard
 
@@ -544,7 +557,7 @@ proc getValue(c: var HtmlCompiler, node: Node,
     if likely(some.scopeTable != nil):
       return c.getValue(some.scopeTable[node.identName].varValue, scopetables)
     compileErrorWithArgs(undeclaredVariable, [node.identName])
-  of ntAssignableSet:
+  of ntAssignableSet, ntIndexRange:
     # return literal nodes
     result = node
   of ntInfixExpr:
diff --git a/src/tim/engine/parser.nim b/src/tim/engine/parser.nim
index adc8492..4502340 100755
--- a/src/tim/engine/parser.nim
+++ b/src/tim/engine/parser.nim
@@ -103,6 +103,12 @@ proc `notin`(tk: TokenTuple, kind: set[TokenKind]): bool {.inline.} =
 proc isFnCall(p: var Parser): bool {.inline.} =
   p.curr is tkIdentifier and p.next is tkLP and p.next.wsno == 0
 
+template isRange: untyped =
+  (
+    (p.curr is tkDot and p.next is tkDot) and
+      (p.curr.line == tk.line and p.next.line == tk.line)
+  )
+
 template expectWalk(kind: TokenKind) =
   if likely(p.curr is kind):
     walk p
@@ -262,25 +268,39 @@ proc parseDotExpr(p: var Parser, lhs: Node): Node {.gcsafe.} =
 
 proc parseBracketExpr(p: var Parser, lhs: Node): Node {.gcsafe.} =
   # parse bracket expression
-  result = ast.newNode(ntBracketExpr, p.prev)
-  walk p # tkLB
+  let tk = p.curr; walk p # tkLB
   let index = p.getPrefixOrInfix()
+  result = ast.newNode(ntBracketExpr, p.curr)
+  result.bracketLHS = lhs
   caseNotNil index:
-    result.bracketIndex = index
-    result.bracketLHS = lhs
-  expectWalk tkRB
-  while true:
-    case p.curr.kind
-    of tkDot:
-      if p.curr.line == result.meta[0]:
-        result = p.parseDotExpr(result)
-      else: break
-    of tkLB:
-      if p.curr.line == result.meta[0]:
-        result = p.parseBracketExpr(result)
-      else: break
-    else:
-      break # todo handle infix expressions
+    if p.curr is tkRB:
+      result.bracketIndex = index
+      while true:
+        case p.curr.kind
+        of tkDot:
+          if p.curr.line == result.meta[0]:
+            result = p.parseDotExpr(result)
+          else: break
+        of tkLB:
+          if p.curr.line == result.meta[0]:
+            result = p.parseBracketExpr(result)
+          else: break
+        else:
+          break # todo handle infix expressions
+    elif isRange:
+      walk p, 2
+      let lastIndex =
+        if p.curr is tkCaret:
+          walk p; true
+        else: false
+      expect {tkInteger, tkIdentVar}:
+        let rhs = p.parsePrefix()
+        caseNotnil rhs:
+          let rangeNode = ast.newNode(ntIndexRange)
+          rangeNode.rangeNodes = [index, rhs]
+          rangeNode.rangeLastIndex = lastIndex
+          result.bracketIndex = rangeNode
+      expectWalk tkRB
 
 prefixHandle pIdent:
   # parse an identifier
@@ -592,7 +612,7 @@ prefixHandle pFor:
       pairNode.identPairs[1] = vNode
       result.loopItem = pairNode
       walk p
-    expectWalk(tkIN)
+    expectWalk tkIN
     expect {tkIdentVar, tkLB}:
       let items = p.parsePrefix()
       caseNotNil items:
diff --git a/src/tim/engine/tokens.nim b/src/tim/engine/tokens.nim
index 4ee9f53..e16d4ba 100755
--- a/src/tim/engine/tokens.nim
+++ b/src/tim/engine/tokens.nim
@@ -156,6 +156,7 @@ registerTokens toktokSettings:
     doc = tokenize(handleDocBlock, '*')
     comment = tokenize(handleInlineComment, '/')
   `mod` = '%'
+  caret = '^'
   lc = '{'
   rc = '}'
   lp = '('