add string.endswith() to efficiently test for a suffix without copying

add string.startswith() to efficiently test for string prefix without copying

codeGenVirtual/src/prog8/codegen/virtual/AssignmentGen.kt

@@ -165,6 +165,11 @@ internal class AssignmentGen(private val codeGen: CodeGen, private val expressio
                     throw AssemblyError("non-array var indexing requires bytes index")
                 val idxReg = codeGen.vmRegisters.nextFree()
                 code += expressionEval.translateExpression(array.index, idxReg, -1)
+                if(zero) {
+                    // there's no STOREZIX instruction
+                    resultRegister = codeGen.vmRegisters.nextFree()
+                    code += VmCodeInstruction(Opcode.LOAD, vmDt, reg1=resultRegister, value=0)
+                }
                 code += VmCodeInstruction(Opcode.STOREIX, vmDt, reg1=resultRegister, reg2=idxReg, value = variableAddr)
                 return code
             }

codeGenVirtual/src/prog8/codegen/virtual/VariableAllocator.kt

@@ -60,8 +60,8 @@ class VariableAllocator(private val st: SymbolTable, private val program: PtProg
                 DataType.FLOAT -> (variable.initialNumericValue ?: 0.0).toString()
                 in NumericDatatypes -> (variable.initialNumericValue ?: 0).toHex()
                 DataType.STR -> {
-                    val encoded = program.encoding.encodeString(variable.initialStringValue!!.first, variable.initialStringValue!!.second)
+                    val encoded = program.encoding.encodeString(variable.initialStringValue!!.first, variable.initialStringValue!!.second) + listOf(0u)
-                    encoded.joinToString(",") { it.toInt().toHex() } + ",0"
+                    encoded.joinToString(",") { it.toInt().toHex() }
                 }
                 DataType.ARRAY_F -> {
                     if(variable.initialArrayValue!=null) {

compiler/res/prog8lib/string.p8

@@ -223,6 +223,26 @@ _done       rts
         }}
     }
 
+    sub startswith(str st, str prefix) -> bool {
+        ubyte prefix_len = length(prefix)
+        ubyte str_len = length(st)
+        if prefix_len > str_len
+            return false
+        cx16.r9L = st[prefix_len]
+        st[prefix_len] = 0
+        cx16.r9H = compare(st, prefix) as ubyte
+        st[prefix_len] = cx16.r9L
+        return cx16.r9H==0
+    }
+
+    sub endswith(str st, str suffix) -> bool {
+        ubyte suffix_len = length(suffix)
+        ubyte str_len = length(st)
+        if suffix_len > str_len
+            return false
+        return compare(st + str_len - suffix_len, suffix) == 0
+    }
+
     asmsub pattern_match(str string @AY, str pattern @R0) clobbers(Y) -> ubyte @A {
 		%asm {{
 ; pattern matching of a string.
@@ -293,5 +313,4 @@ fail    clc             ; yes, no match found, return with c=0
 	rts
 		}}
 	}
-
 }

compiler/res/prog8lib/virtual/string.p8

@@ -113,4 +113,24 @@ string {
             ix++
         }
     }
+
+    sub startswith(str st, str prefix) -> bool {
+        ubyte prefix_len = length(prefix)
+        ubyte str_len = length(st)
+        if prefix_len > str_len
+            return false
+        cx16.r9L = st[prefix_len]
+        st[prefix_len] = 0
+        cx16.r9H = compare(st, prefix) as ubyte
+        st[prefix_len] = cx16.r9L
+        return cx16.r9H==0
+    }
+
+    sub endswith(str st, str suffix) -> bool {
+        ubyte suffix_len = length(suffix)
+        ubyte str_len = length(st)
+        if suffix_len > str_len
+            return false
+        return compare(st + str_len - suffix_len, suffix) == 0
+    }
 }

compiler/res/version.txt

@@ -1 +1 @@
-8.3.1
+8.4-dev

docs/source/libraries.rst

@@ -190,6 +190,16 @@ Provides string manipulation routines.
 ``upper(string)``
     Uppercases the petscii-string in place.
 
+``startswith(string, prefix) -> bool``
+    Returns true if string starts with prefix, otherwise false
+
+``endswith(string, suffix) -> bool``
+    Returns true if string ends with suffix, otherwise false
+
+``pattern_match(string, pattern) -> ubyte`` (not on Virtual target)
+    Returns 1 (true) if the string matches the pattern, 0 (false) if not.
+    '?' in the pattern matches any one character. '*' in the pattern matches any substring.
+
 
 floats
 ------

docs/source/todo.rst

@@ -3,6 +3,8 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
+- can the recursive cycle detector print the actual LINES that do the call?
+
 ...