plugeth/lib/abi.js

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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;
};
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var findMethodIndex = function (json, methodName) {
return findIndex(json, function (method) {
return method.name === methodName;
});
};
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var padLeft = function (number, n) {
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return (new Array(n * 2 - number.toString().length + 1)).join("0") + number;
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};
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var setupInputTypes = function () {
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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);
};
};
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var namedType = function (name, padding, formatter) {
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return function (type, value) {
if (type !== name) {
return false;
}
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return padLeft(formatter ? value : formatter(value), padding);
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};
};
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var formatBool = function (value) {
return value ? '1' : '0';
};
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return [
prefixedType('uint'),
prefixedType('int'),
namedType('address', 20),
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namedType('bool', 1, formatBool),
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];
};
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var inputTypes = setupInputTypes();
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var toAbiInput = function (json, methodName, params) {
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var bytes = "";
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var index = findMethodIndex(json, methodName);
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if (index === -1) {
return;
}
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// it needs to be checked in WebThreeStubServer
// something wrong might be with this additional zero
bytes = bytes + index + 'x' + '0';
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var method = json[index];
for (var i = 0; i < method.inputs.length; i++) {
var found = false;
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for (var j = 0; j < inputTypes.length && !found; j++) {
found = inputTypes[j](method.inputs[i].type, params[i]);
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}
if (!found) {
console.error('unsupported json type: ' + method.inputs[i].type);
}
bytes += found;
}
return bytes;
};
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var setupOutputTypes = function () {
var prefixedType = function (prefix) {
return function (type) {
var expected = prefix;
if (type.indexOf(expected) !== 0) {
return -1;
}
var padding = parseInt(type.slice(expected.length)) / 8;
return padding * 2;
};
};
var namedType = function (name, padding) {
return function (type) {
return name === type ? padding * 2: -1;
};
};
var formatInt = function (value) {
return parseInt(value, 16);
};
var formatBool = function (value) {
return value === '1' ? true : false;
};
return [
{ padding: prefixedType('uint'), format: formatInt },
{ padding: prefixedType('int'), format: formatInt },
{ padding: namedType('address', 20) },
{ padding: namedType('bool', 1), format: formatBool }
];
};
var outputTypes = setupOutputTypes();
var fromAbiOutput = function (json, methodName, output) {
var index = findMethodIndex(json, methodName);
if (index === -1) {
return;
}
output = output.slice(2);
var result = [];
var method = json[index];
for (var i = 0; i < method.outputs.length; i++) {
var padding = -1;
for (var j = 0; j < outputTypes.length && padding === -1; j++) {
padding = outputTypes[j].padding(method.outputs[i].type);
}
if (padding === -1) {
// not found output parsing
continue;
}
var res = output.slice(0, padding);
var formatter = outputTypes[j - 1].format;
result.push(formatter ? formatter(res): res);
output = output.slice(padding);
}
return result;
};
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var load = function (json) {
var contract = {};
json.forEach(function (method) {
contract[method.name] = function () {
var params = Array.prototype.slice.call(arguments);
return toAbiInput(json, method.name, params);
};
});
return contract;
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};
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module.exports = load;