prepare parser to allow chained array indexing later

compilerAst/src/prog8/ast/antlr/Antlr2Kotlin.kt

@@ -317,9 +317,10 @@ private fun Prog8ANTLRParser.Assign_targetContext.toAst() : AssignTarget {
         is MemoryTargetContext ->
             AssignTarget(null, null, DirectMemoryWrite(directmemory().expression().toAst(), directmemory().toPosition()), toPosition())
         is ArrayindexedTargetContext -> {
-            val arrayvar = scoped_identifier().toAst()
+            val ax = arrayindexed()
-            val index = arrayindex().toAst()
+            val arrayvar = ax.scoped_identifier().toAst()
-            val arrayindexed = ArrayIndexedExpression(arrayvar, index, scoped_identifier().toPosition())
+            val index = ax.arrayindex().toAst()
+            val arrayindexed = ArrayIndexedExpression(arrayvar, index, ax.toPosition())
             AssignTarget(null, arrayindexed, null, toPosition())
         }
         else -> throw FatalAstException("weird assign target node $this")
@@ -434,10 +435,11 @@ private fun Prog8ANTLRParser.ExpressionContext.toAst() : Expression {
         }
     }
 
-    if(arrayindex()!=null) {
+    if(arrayindexed()!=null) {
-        val identifier = scoped_identifier().toAst()
+        val ax = arrayindexed()
-        val index = arrayindex().toAst()
+        val identifier = ax.scoped_identifier().toAst()
-        return ArrayIndexedExpression(identifier, index, scoped_identifier().toPosition())
+        val index = ax.arrayindex().toAst()
+        return ArrayIndexedExpression(identifier, index, ax.toPosition())
     }
 
     if(scoped_identifier()!=null)

docs/source/todo.rst

@@ -1,8 +1,7 @@
 TODO
 ====
-- prefix prog8 subroutines with p8s_ instead of p8_ to not let them clash with variables in the asm?
+
-- allow 'chained' array indexing for expressions:  value = ptrarray[0][0]
+- prefix prog8 subroutines with p8s_ instead of p8_ to not let them clash with variables in the asm??
-- allow 'chained' array indexing for assign targets:  ptrarray[0][0] = 42   this is just evaluating the lhs as a uword pointer expression
 - [on branch: shortcircuit] investigate McCarthy evaluation again? this may also reduce code size perhaps for things like if a>4 or a<2 ....
 - IR: reduce the number of branch instructions such as BEQ, BEQR, etc (gradually), replace with CMP(I) + status branch instruction
 - IR: reduce amount of CMP/CMPI after instructions that set the status bits correctly (LOADs? INC? etc), but only after setting the status bits is verified!
@@ -21,6 +20,9 @@ Future Things and Ideas
 ^^^^^^^^^^^^^^^^^^^^^^^
 Compiler:
 
+- allow 'chained' array indexing for expressions:  value = ptrarray[0][0]
+- allow 'chained' array indexing for assign targets:  ptrarray[0][0] = 42   this is just evaluating the lhs as a uword pointer expression
+
 - [much work:] more support for (64tass) SEGMENTS ?
     - (What, how, isn't current BSS support enough?)
     - Add a mechanism to allocate variables into golden ram (or segments really) (see GoldenRam class)

parser/antlr/Prog8ANTLR.g4

@@ -153,7 +153,7 @@ augassignment :
 
 assign_target:
 	scoped_identifier               #IdentifierTarget
-	| scoped_identifier arrayindex  #ArrayindexedTarget        // TODO expression instead of just scoped_identifier
+	| arrayindexed                  #ArrayindexedTarget
 	| directmemory                  #MemoryTarget
 	;
 
@@ -180,12 +180,18 @@ expression :
 	| left = expression EOL? bop = 'xor' EOL? right = expression
 	| literalvalue
 	| scoped_identifier
-	| scoped_identifier arrayindex          // TODO expression instead of just scoped_identifier
+	| arrayindexed
 	| directmemory
 	| addressof
 	| expression typecast
 	;
 
+arrayindexed:
+    scoped_identifier arrayindex
+    // TODO to allow chained array indexing:  | arrayindexed arrayindex
+    ;
+
+
 typecast : 'as' datatype;
 
 directmemory : '@' '(' expression ')';