quick and dirty implementations of some string functions

js-assembler/assemble-helpers.rkt

@@ -125,6 +125,8 @@
                (assemble-numeric-constant val)]
               [(string? val)
                (format "~s" val)]
+              [(char? val)
+               (format "RUNTIME.makeChar(~s)" (string val))]
               [(bytes? val)
                (format "RUNTIME.makeBytes(~a)"
                        (string-join (for/list ([a-byte val])

js-assembler/runtime-src/baselib-primitives.js

@@ -69,6 +69,8 @@
     var checkRational = baselib.check.checkRational;
     var checkPair = baselib.check.checkPair;
     var checkList = baselib.check.checkList;
+    var checkListofChars = baselib.check.makeCheckListofArgumentType(baselib.chars.isChar,
+                                                                     'character');
     var checkVector = baselib.check.checkVector;
     var checkBox = baselib.check.checkBox;
     var checkMutableBox = baselib.check.checkMutableBox;
@@ -619,6 +621,34 @@
             return baselib.strings.makeMutableString(arr);
         });
 
+    installPrimitiveProcedure(
+        'substring',
+        makeList(2, 3),
+        function(MACHINE) {
+            var str = String(checkString(MACHINE, 'substring', 0));
+            var start = baselib.numbers.toFixnum(checkNatural(MACHINE, 'substring', 1));
+            var end = str.length;
+            if (MACHINE.argcount === 3) {
+                end = baselib.numbers.toFixnum(checkNatural(MACHINE, 'substring', 2));
+            }
+            return str.substring(start, end);
+        });
+
+
+    installPrimitiveProcedure(
+        'list->string',
+        1,
+        function (MACHINE) {
+            var firstArg = checkListofChars(MACHINE, 'list->string', 0);
+            var result = [];
+            while (firstArg !== NULL) {
+                result.push(firstArg.first.val);
+                firstArg = firstArg.rest;
+            }
+            return result.join('');
+        });
+
+
 
     installPrimitiveProcedure(
         'string-set!',

js-assembler/runtime-src/runtime.js

@@ -54,6 +54,7 @@
     var makeVector = baselib.vectors.makeVector;
     var makeList = baselib.lists.makeList;
     var makePair = baselib.lists.makePair;
+    var makeChar = baselib.chars.makeChar;
 
     var makeStructureType = baselib.structs.makeStructureType;
 
@@ -671,6 +672,7 @@
     // numbers
     exports['makeList'] = makeList;
     exports['makePair'] = makePair;
+    exports['makeChar'] = makeChar;
     exports['makeVector'] = makeVector;
     exports['makeBox'] = makeBox;
     exports['makeFloat'] = makeFloat;

lang/kernel.rkt

@@ -353,10 +353,10 @@ memq
 ;;  string-ci>?
 ;;  string-ci<=?
 ;;  string-ci>=?
-;;  substring
+  substring
   string-append
 ;;  string->list
-;;  list->string
+  list->string
 ;;  string-copy
 string->symbol
 symbol->string

tests/more-tests/string-tests.expected

@@ -0,0 +1,15 @@
+"hello world"
+"ello world"
+"llo world"
+"lo world"
+"hello world"
+""
+"e"
+"el"
+""
+"l"
+""
+"l"
+"lo"
+""
+"hello"

tests/more-tests/string-tests.rkt

@@ -0,0 +1,19 @@
+#lang planet dyoo/whalesong
+
+(substring "hello world" 0)
+(substring "hello world" 1)
+(substring "hello world" 2)
+(substring "hello world" 3)
+(substring "hello world" 0)
+(substring "hello world" 1 1)
+(substring "hello world" 1 2)
+(substring "hello world" 1 3)
+(substring "hello world" 2 2)
+(substring "hello world" 2 3)
+(substring "hello world" 3 3)
+(substring "hello world" 3 4)
+(substring "hello world" 3 5)
+
+
+(list->string '())
+(list->string '(#\h #\e #\l #\l #\o))

tests/run-more-tests.rkt

@@ -6,6 +6,7 @@
 ;; content vs. a text file with the same name, but with the .rkt file
 ;; type replaced with .expected.
 
+(test "more-tests/string-tests.rkt")
 (test "more-tests/hello.rkt")
 (test "more-tests/simple-functions.rkt")
 (test "more-tests/sk-generator.rkt")