1 files changed, 151 insertions, 0 deletions
diff --git a/py/objstr.c b/py/objstr.c
new file mode 100644
index 0000000000..d82ea3d3ce
--- /dev/null
+++ b/py/objstr.c
@@ -0,0 +1,151 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdarg.h>
+#include <string.h>
+#include <assert.h>
+
+#include "nlr.h"
+#include "misc.h"
+#include "mpconfig.h"
+#include "obj.h"
+#include "runtime0.h"
+#include "runtime.h"
+
+typedef struct _mp_obj_str_t {
+    mp_obj_base_t base;
+    qstr qstr;
+} mp_obj_str_t;
+
+void str_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in) {
+    mp_obj_str_t *self = self_in;
+    // TODO need to escape chars etc
+    print(env, "'%s'", qstr_str(self->qstr));
+}
+
+mp_obj_t str_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
+    mp_obj_str_t *lhs = lhs_in;
+    const char *lhs_str = qstr_str(lhs->qstr);
+    switch (op) {
+        case RT_BINARY_OP_SUBSCR:
+            // string access
+            // XXX a massive hack!
+            return mp_obj_new_int(lhs_str[mp_obj_get_int(rhs_in)]);
+
+        case RT_BINARY_OP_ADD:
+        case RT_BINARY_OP_INPLACE_ADD:
+            if (MP_OBJ_IS_TYPE(rhs_in, &str_type)) {
+                // add 2 strings
+                const char *rhs_str = qstr_str(((mp_obj_str_t*)rhs_in)->qstr);
+                char *val = m_new(char, strlen(lhs_str) + strlen(rhs_str) + 1);
+                stpcpy(stpcpy(val, lhs_str), rhs_str);
+                return mp_obj_new_str(qstr_from_str_take(val));
+            }
+            break;
+    }
+
+    return MP_OBJ_NULL; // op not supported
+}
+
+mp_obj_t str_join(mp_obj_t self_in, mp_obj_t arg) {
+    assert(MP_OBJ_IS_TYPE(self_in, &str_type));
+    mp_obj_str_t *self = self_in;
+    int required_len = strlen(qstr_str(self->qstr));
+
+    // process arg, count required chars
+    uint seq_len;
+    mp_obj_t *seq_items;
+    if (MP_OBJ_IS_TYPE(arg, &tuple_type)) {
+        mp_obj_tuple_get(arg, &seq_len, &seq_items);
+    } else if (MP_OBJ_IS_TYPE(arg, &list_type)) {
+        mp_obj_list_get(arg, &seq_len, &seq_items);
+    } else {
+        goto bad_arg;
+    }
+    for (int i = 0; i < seq_len; i++) {
+        if (!MP_OBJ_IS_TYPE(seq_items[i], &str_type)) {
+            goto bad_arg;
+        }
+        required_len += strlen(qstr_str(mp_obj_str_get(seq_items[i])));
+    }
+
+    // make joined string
+    char *joined_str = m_new(char, required_len + 1);
+    joined_str[0] = 0;
+    for (int i = 0; i < seq_len; i++) {
+        const char *s2 = qstr_str(mp_obj_str_get(seq_items[i]));
+        if (i > 0) {
+            strcat(joined_str, qstr_str(self->qstr));
+        }
+        strcat(joined_str, s2);
+    }
+    return mp_obj_new_str(qstr_from_str_take(joined_str));
+
+bad_arg:
+    nlr_jump(mp_obj_new_exception_msg(rt_q_TypeError, "?str.join expecting a list of str's"));
+}
+
+void vstr_printf_wrapper(void *env, const char *fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+    vstr_vprintf(env, fmt, args);
+    va_end(args);
+}
+
+mp_obj_t str_format(int n_args, const mp_obj_t *args) {
+    assert(MP_OBJ_IS_TYPE(args[0], &str_type));
+    mp_obj_str_t *self = args[0];
+
+    const char *str = qstr_str(self->qstr);
+    int arg_i = 1;
+    vstr_t *vstr = vstr_new();
+    for (; *str; str++) {
+        if (*str == '{') {
+            str++;
+            if (*str == '{') {
+                vstr_add_char(vstr, '{');
+            } else if (*str == '}') {
+                if (arg_i >= n_args) {
+                    nlr_jump(mp_obj_new_exception_msg(rt_q_IndexError, "tuple index out of range"));
+                }
+                mp_obj_print_helper(vstr_printf_wrapper, vstr, args[arg_i]);
+                arg_i++;
+            }
+        } else {
+            vstr_add_char(vstr, *str);
+        }
+    }
+
+    return mp_obj_new_str(qstr_from_str_take(vstr->buf));
+}
+
+static MP_DEFINE_CONST_FUN_OBJ_2(str_join_obj, str_join);
+static MP_DEFINE_CONST_FUN_OBJ_VAR(str_format_obj, 1, str_format);
+
+const mp_obj_type_t str_type = {
+    { &mp_const_type },
+    "str",
+    str_print, // print
+    NULL, // call_n
+    NULL, // unary_op
+    str_binary_op, // binary_op
+    NULL, // getiter
+    NULL, // iternext
+    { // method list
+        { "join", &str_join_obj },
+        { "format", &str_format_obj },
+        { NULL, NULL }, // end-of-list sentinel
+    },
+};
+
+mp_obj_t mp_obj_new_str(qstr qstr) {
+    mp_obj_str_t *o = m_new_obj(mp_obj_str_t);
+    o->base.type = &str_type;
+    o->qstr = qstr;
+    return o;
+}
+
+qstr mp_obj_str_get(mp_obj_t self_in) {
+    assert(MP_OBJ_IS_TYPE(self_in, &str_type));
+    mp_obj_str_t *self = self_in;
+    return self->qstr;
+}