abi, the beginning

1 files changed, 77 insertions, 0 deletions

diff --git a/lib/abi.js b/lib/abi.js
new file mode 100644
index 000000000..3082b8232
--- /dev/null
+++ b/lib/abi.js
@@ -0,0 +1,77 @@
+
+var findIndex = function (array, callback) {
+    var end = false;
+    var i = 0;
+    for (; i < array.length && !end; i++) {
+        end = callback(array[i]);
+    }
+    return end ? i - 1 : -1;
+};
+
+var padLeft = function (number, n) {
+    return (new Array(n - number.toString.length + 1)).join("0") + number;
+};
+
+var setupTypes = function () {
+    var prefixedType = function (prefix) {
+        return function (type, value) {
+            var expected = prefix;
+            if (type.indexOf(expected) !== 0) {
+                return false;
+            }
+
+            var padding = parseInt(type.slice(expected.length)) / 8;
+            return padLeft(value, padding);
+        };
+    };
+
+    var namedType = function (name, padding) {
+        return function (type, value) {
+            if (type !== name) {
+                return false; 
+            }
+
+            return padLeft(value, padding);
+        };
+    };
+
+    return [
+        prefixedType('uint'),
+        prefixedType('int'),
+        namedType('address', 20),
+        namedType('bool', 1),
+    ];
+};
+
+var types = setupTypes();
+
+var toBytes = function (json, methodName, params) {
+    var bytes = "";
+    var index = findIndex(json, function (method) {
+        return method.name === methodName;
+    });
+
+    if (index === -1) {
+        return;
+    }
+
+    bytes = bytes + index + 'x';
+    var method = json[index];
+    
+    for (var i = 0; i < method.inputs.length; i++) {
+        var found = false;
+        for (var j = 0; j < types.length && !found; j++) {
+            found = types[j](method.inputs[i].type, params[i]);
+        }
+        if (!found) {
+            console.error('unsupported json type: ' + method.inputs[i].type);
+        }
+        bytes += found;
+    }
+    return bytes;
+};
+
+module.exports = {
+    toBytes: toBytes
+};
+