More robust/simple signature parsing, using a parse tree

4 files changed, 146 insertions, 98 deletions

diff --git a/packages/utils/src/abi_encoder/evm_data_type_factory.ts b/packages/utils/src/abi_encoder/evm_data_type_factory.ts
index 268649148..613eb887f 100644
--- a/packages/utils/src/abi_encoder/evm_data_type_factory.ts
+++ b/packages/utils/src/abi_encoder/evm_data_type_factory.ts
@@ -2,7 +2,7 @@
 import { DataItem, MethodAbi } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { generateDataItemsFromSignature } from './utils/signature_parser';
+import { generateDataItemFromSignature } from './utils/signature_parser';
 
 import { DataType } from './abstract_data_types/data_type';
 import { DataTypeFactory } from './abstract_data_types/interfaces';
@@ -134,32 +134,87 @@ export class EvmDataTypeFactory implements DataTypeFactory {
 
 /**
  * Convenience function for creating a DataType from different inputs.
- * @param input A single or set of DataItem or a DataType signature.
- *              A signature in the form of '<type>' is interpreted as a `DataItem`
- *              For example, 'string' is interpreted as {type: 'string'}
- *              A signature in the form '(<type1>, <type2>, ..., <typen>)' is interpreted as `DataItem[]`
- *              For eaxmple, '(string, uint256)' is interpreted as [{type: 'string'}, {type: 'uint256'}]
+ * @param input A single or set of DataItem or a signature for an EVM data type.
  * @return DataType corresponding to input.
  */
 export function create(input: DataItem | DataItem[] | string): DataType {
-    // Handle different types of input
-    const isSignature = typeof input === 'string';
-    const isTupleSignature = isSignature && (input as string).startsWith('(');
-    const shouldParseAsTuple = isTupleSignature || _.isArray(input);
-    // Create input `dataItem`
+    const dataItem = consolidateDataItemsIntoSingle(input);
+    const dataType = EvmDataTypeFactory.getInstance().create(dataItem);
+    return dataType;
+}
+
+/**
+ * Convenience function to aggregate a single input or a set of inputs into a single DataItem.
+ * An array of data items is grouped into a single tuple.
+ * @param input A single data item; a set of data items; a signature.
+ * @return A single data item corresponding to input.
+ */
+function consolidateDataItemsIntoSingle(input: DataItem | DataItem[] | string): DataItem {
     let dataItem: DataItem;
-    if (shouldParseAsTuple) {
-        const dataItems = isSignature ? generateDataItemsFromSignature(input as string) : (input as DataItem[]);
+    if (_.isArray(input)) {
+        const dataItems = input as DataItem[];
         dataItem = {
             name: '',
             type: 'tuple',
             components: dataItems,
         };
     } else {
-        dataItem = isSignature ? generateDataItemsFromSignature(input as string)[0] : (input as DataItem);
+        dataItem = typeof input === 'string' ? generateDataItemFromSignature(input) : (input as DataItem);
     }
-    // Create data type
-    const dataType = EvmDataTypeFactory.getInstance().create(dataItem);
+    return dataItem;
+}
+
+/**
+ * Convenience function for creating a Method encoder from different inputs.
+ * @param methodName name of method.
+ * @param input A single data item; a set of data items; a signature; or an array of signatures (optional).
+ * @param output A single data item; a set of data items; a signature; or an array of signatures (optional).
+ * @return Method corresponding to input.
+ */
+export function createMethod(
+    methodName: string,
+    input?: DataItem | DataItem[] | string | string[],
+    output?: DataItem | DataItem[] | string | string[],
+): Method {
+    const methodInput = _.isUndefined(input) ? [] : consolidateDataItemsIntoArray(input);
+    const methodOutput = _.isUndefined(output) ? [] : consolidateDataItemsIntoArray(output);
+    const methodAbi: MethodAbi = {
+        name: methodName,
+        inputs: methodInput,
+        outputs: methodOutput,
+        type: 'function',
+        // default fields not used by ABI
+        constant: false,
+        payable: false,
+        stateMutability: 'nonpayable',
+    };
+    const dataType = new Method(methodAbi);
     return dataType;
 }
+
+/**
+ * Convenience function that aggregates a single input or a set of inputs into an array of DataItems.
+ * @param input A single data item; a set of data items; a signature; or an array of signatures.
+ * @return Array of data items corresponding to input.
+ */
+function consolidateDataItemsIntoArray(input: DataItem | DataItem[] | string | string[]): DataItem[] {
+    let dataItems: DataItem[];
+    if (_.isArray(input) && _.isEmpty(input)) {
+        dataItems = [];
+    } else if (_.isArray(input) && typeof input[0] === 'string') {
+        dataItems = [];
+        _.each(input as string[], (signature: string) => {
+            const dataItem = generateDataItemFromSignature(signature);
+            dataItems.push(dataItem);
+        });
+    } else if (_.isArray(input)) {
+        dataItems = input as DataItem[];
+    } else if (typeof input === 'string') {
+        const dataItem = generateDataItemFromSignature(input);
+        dataItems = [dataItem];
+    } else {
+        dataItems = [input as DataItem];
+    }
+    return dataItems;
+}
 /* tslint:enable no-construct */
diff --git a/packages/utils/src/abi_encoder/evm_data_types/method.ts b/packages/utils/src/abi_encoder/evm_data_types/method.ts
index c852a0fdf..93746fa00 100644
--- a/packages/utils/src/abi_encoder/evm_data_types/method.ts
+++ b/packages/utils/src/abi_encoder/evm_data_types/method.ts
@@ -65,6 +65,11 @@ export class MethodDataType extends AbstractSetDataType {
         return this._methodSelector;
     }
 
+    public getReturnValueDataItem(): DataItem {
+        const returnValueDataItem = this._returnDataType.getDataItem();
+        return returnValueDataItem;
+    }
+
     private _computeSignature(): string {
         const memberSignature = this._computeSignatureOfMembers();
         const methodSignature = `${this.getDataItem().name}${memberSignature}`;
diff --git a/packages/utils/src/abi_encoder/index.ts b/packages/utils/src/abi_encoder/index.ts
index cfacfe075..976bac8e6 100644
--- a/packages/utils/src/abi_encoder/index.ts
+++ b/packages/utils/src/abi_encoder/index.ts
@@ -12,5 +12,6 @@ export {
     Tuple,
     UInt,
     create,
+    createMethod,
 } from './evm_data_type_factory';
 export { DataType } from './abstract_data_types/data_type';
diff --git a/packages/utils/src/abi_encoder/utils/signature_parser.ts b/packages/utils/src/abi_encoder/utils/signature_parser.ts
index 315784cea..d3996bf8e 100644
--- a/packages/utils/src/abi_encoder/utils/signature_parser.ts
+++ b/packages/utils/src/abi_encoder/utils/signature_parser.ts
@@ -1,101 +1,88 @@
 import { DataItem } from 'ethereum-types';
 import * as _ from 'lodash';
 
+interface Node {
+    name: string;
+    value: string;
+    children: Node[];
+    parent?: Node;
+}
+
+function parseNode(node: Node): DataItem {
+    const components: DataItem[] = [];
+    _.each(node.children, (child: Node) => {
+        const component = parseNode(child);
+        components.push(component);
+    });
+    const dataItem: DataItem = {
+        name: node.name,
+        type: node.value,
+    };
+    if (!_.isEmpty(components)) {
+        dataItem.components = components;
+    }
+    return dataItem;
+}
+
 /**
- * Returns an array of DataItem's corresponding to the input signature.
- * A signature can be in two forms: '<DataItem.type>' or '(<DataItem1.type>, <DataItem2.type>, ...)
- * An example of the first form would be 'address' or 'uint256'
- * An example of the second form would be '(address, uint256)'
- * Signatures can also include a name field, for example: 'foo address' or '(foo address, bar uint256)'
- * @param signature of input DataItems
- * @return DataItems derived from input signature
+ * Returns a DataItem corresponding to the input signature.
+ * A signature can be in two forms: `type` or `(type_1,type_2,...,type_n)`
+ * An example of the first form would be 'address' or 'uint256[]' or 'bytes[5][]'
+ * An example of the second form would be '(address,uint256)' or '(address,uint256)[]'
+ * @param signature of input DataItem.
+ * @return DataItem derived from input signature.
  */
-export function generateDataItemsFromSignature(signature: string): DataItem[] {
-    let trimmedSignature = signature;
-    if (signature.startsWith('(')) {
-        if (!signature.endsWith(')')) {
-            throw new Error(`Failed to generate data item. Must end with ')'`);
-        }
-        trimmedSignature = signature.substr(1, signature.length - 2);
+export function generateDataItemFromSignature(signature: string): DataItem {
+    // No data item corresponds to an empty signature
+    if (_.isEmpty(signature)) {
+        throw new Error(`Cannot parse data item from empty signature, ''`);
     }
-    trimmedSignature += ',';
-    let isCurrTokenArray = false;
-    let currTokenArrayModifier = '';
-    let isParsingArrayModifier = false;
-    let currToken = '';
-    let parenCount = 0;
-    let currTokenName = '';
-    const dataItems: DataItem[] = [];
-    for (const char of trimmedSignature) {
-        // Tokenize the type string while keeping track of parentheses.
+    // Create a parse tree for data item
+    let node: Node = {
+        name: '',
+        value: '',
+        children: [],
+    };
+    for (const char of signature) {
         switch (char) {
             case '(':
-                parenCount += 1;
-                currToken += char;
+                const child = {
+                    name: '',
+                    value: '',
+                    children: [],
+                    parent: node,
+                };
+                node.value = 'tuple';
+                node.children.push(child);
+                node = child;
                 break;
+
             case ')':
-                parenCount -= 1;
-                currToken += char;
+                node = node.parent as Node;
                 break;
-            case '[':
-                if (parenCount === 0) {
-                    isParsingArrayModifier = true;
-                    isCurrTokenArray = true;
-                    currTokenArrayModifier += '[';
-                } else {
-                    currToken += char;
-                }
-                break;
-            case ']':
-                if (parenCount === 0) {
-                    isParsingArrayModifier = false;
-                    currTokenArrayModifier += ']';
-                } else {
-                    currToken += char;
-                }
+
+            case ',':
+                const sibling = {
+                    name: '',
+                    value: '',
+                    children: [],
+                    parent: node.parent,
+                };
+                (node.parent as Node).children.push(sibling);
+                node = sibling;
                 break;
+
             case ' ':
-                if (parenCount === 0) {
-                    currTokenName = currToken;
-                    currToken = '';
-                } else {
-                    currToken += char;
-                }
+                node.name = node.value;
+                node.value = '';
                 break;
-            case ',':
-                if (parenCount === 0) {
-                    // Generate new DataItem from token
-                    const components = currToken.startsWith('(') ? generateDataItemsFromSignature(currToken) : [];
-                    const isTuple = !_.isEmpty(components);
-                    const dataItem: DataItem = { name: currTokenName, type: '' };
-                    if (isTuple) {
-                        dataItem.type = 'tuple';
-                        dataItem.components = components;
-                    } else {
-                        dataItem.type = currToken;
-                    }
-                    if (isCurrTokenArray) {
-                        dataItem.type += currTokenArrayModifier;
-                    }
-                    dataItems.push(dataItem);
-                    // reset token state
-                    currTokenName = '';
-                    currToken = '';
-                    isCurrTokenArray = false;
-                    currTokenArrayModifier = '';
-                    break;
-                } else {
-                    currToken += char;
-                    break;
-                }
+
             default:
-                if (isParsingArrayModifier) {
-                    currTokenArrayModifier += char;
-                } else {
-                    currToken += char;
-                }
+                node.value += char;
                 break;
         }
     }
-    return dataItems;
+    // Interpret data item from parse tree
+    const dataItem = parseNode(node);
+    return dataItem;
 }