Moved luaH_getn to ltable.js

1 files changed, 30 insertions, 0 deletions

diff --git a/src/ltable.js b/src/ltable.js
new file mode 100644
index 0000000..6e3af15
--- /dev/null
+++ b/src/ltable.js
@@ -0,0 +1,30 @@
+/*jshint esversion: 6 */
+"use strict";
+
+const lobject = require('./lobject.js');
+const Table   = lobject.Table;
+
+/*
+** Try to find a boundary in table 't'. A 'boundary' is an integer index
+** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
+*/
+Table.prototype.luaH_getn = function() {
+    let array = this.value.array;
+    let hash = this.value.hash;
+
+    let j = array.length;
+    if (j > 0 && array[j - 1].ttisnil()) {
+        /* there is a boundary in the array part: (binary) search for it */
+        let i = 0;
+        while (j - i > 1) {
+            let m = (i+j)/2;
+            if (array[m - 1].ttisnil()) j = m;
+            else i = m;
+        }
+        return i;
+    }
+    /* else must find a boundary in hash part */
+    else if (hash.size === 0)
+        return j;
+    else return j; // TODO: unbound_search(t, j) => but why ?
+};
\ No newline at end of file