Merge branch 'development' into fix/instant/signature-denied

* development: (914 commits)
  Unfix compiler version except for top level contracts
  Move OrderValidator to extensions
  Update CHANGELOG
  Remove assembly version of matchOrders
  Add getOrderInfo check before calling fillOrder
  Update comments and hard code function selector constants
  Fix build after rebase
  update comments
  Fix build and add back tests
  Update dependency paths
  Add OrderMatcher tests
  feat: Add OrderMatcher contract that takes spread in multiple assets by calling `matchOrders` followed by `fillOrder`
  Update CHANGELOG
  Use more efficient equality checks
  Add note about input validation
  Use more efficient check for overflow
  Check if amount == 0 before doing division
  Reapply prettier
  New relayers
  feat(sra_client.py): Test deployed pkg via tox
  ...

8 files changed, 328 insertions, 192 deletions

diff --git a/packages/sol-compiler/CHANGELOG.json b/packages/sol-compiler/CHANGELOG.json
index 0a757f519..8548fd73f 100644
--- a/packages/sol-compiler/CHANGELOG.json
+++ b/packages/sol-compiler/CHANGELOG.json
@@ -1,5 +1,18 @@
 [
     {
+        "version": "2.0.0",
+        "changes": [
+            {
+                "note": "Add sol-compiler watch mode with -w flag",
+                "pr": 1461
+            },
+            {
+                "note": "Make error and warning colouring more visually pleasant and consistent with other compilers",
+                "pr": 1461
+            }
+        ]
+    },
+    {
         "version": "1.1.16",
         "changes": [
             {
diff --git a/packages/sol-compiler/package.json b/packages/sol-compiler/package.json
index 0ad620b1f..86167a603 100644
--- a/packages/sol-compiler/package.json
+++ b/packages/sol-compiler/package.json
@@ -44,7 +44,9 @@
     "devDependencies": {
         "@0x/dev-utils": "^1.0.21",
         "@0x/tslint-config": "^2.0.0",
+        "@types/chokidar": "^1.7.5",
         "@types/mkdirp": "^0.5.2",
+        "@types/pluralize": "^0.0.29",
         "@types/require-from-string": "^1.2.0",
         "@types/semver": "^5.5.0",
         "chai": "^4.0.1",
@@ -74,10 +76,12 @@
         "@0x/web3-wrapper": "^3.2.1",
         "@types/yargs": "^11.0.0",
         "chalk": "^2.3.0",
+        "chokidar": "^2.0.4",
         "ethereum-types": "^1.1.4",
         "ethereumjs-util": "^5.1.1",
         "lodash": "^4.17.5",
         "mkdirp": "^0.5.1",
+        "pluralize": "^7.0.0",
         "require-from-string": "^2.0.1",
         "semver": "5.5.0",
         "solc": "^0.4.23",
diff --git a/packages/sol-compiler/src/cli.ts b/packages/sol-compiler/src/cli.ts
index 0a9db6e05..18cc68aaf 100644
--- a/packages/sol-compiler/src/cli.ts
+++ b/packages/sol-compiler/src/cli.ts
@@ -25,6 +25,10 @@ const SEPARATOR = ',';
             type: 'string',
             description: 'comma separated list of contracts to compile',
         })
+        .option('watch', {
+            alias: 'w',
+            default: false,
+        })
         .help().argv;
     const contracts = _.isUndefined(argv.contracts)
         ? undefined
@@ -37,7 +41,11 @@ const SEPARATOR = ',';
         contracts,
     };
     const compiler = new Compiler(opts);
-    await compiler.compileAsync();
+    if (argv.watch) {
+        await compiler.watchAsync();
+    } else {
+        await compiler.compileAsync();
+    }
 })().catch(err => {
     logUtils.log(err);
     process.exit(1);
diff --git a/packages/sol-compiler/src/compiler.ts b/packages/sol-compiler/src/compiler.ts
index 85df8209e..d38ccbf39 100644
--- a/packages/sol-compiler/src/compiler.ts
+++ b/packages/sol-compiler/src/compiler.ts
@@ -6,26 +6,29 @@ import {
     NPMResolver,
     RelativeFSResolver,
     Resolver,
+    SpyResolver,
     URLResolver,
 } from '@0x/sol-resolver';
-import { fetchAsync, logUtils } from '@0x/utils';
-import chalk from 'chalk';
+import { logUtils } from '@0x/utils';
+import * as chokidar from 'chokidar';
 import { CompilerOptions, ContractArtifact, ContractVersionData, StandardOutput } from 'ethereum-types';
-import * as ethUtil from 'ethereumjs-util';
 import * as fs from 'fs';
 import * as _ from 'lodash';
 import * as path from 'path';
-import * as requireFromString from 'require-from-string';
+import * as pluralize from 'pluralize';
 import * as semver from 'semver';
 import solc = require('solc');
 
 import { compilerOptionsSchema } from './schemas/compiler_options_schema';
 import { binPaths } from './solc/bin_paths';
 import {
+    addHexPrefixToContractBytecode,
+    compile,
     createDirIfDoesNotExistAsync,
     getContractArtifactIfExistsAsync,
-    getNormalizedErrMsg,
-    parseDependencies,
+    getSolcAsync,
+    getSourcesWithDependencies,
+    getSourceTreeHash,
     parseSolidityVersionRange,
 } from './utils/compiler';
 import { constants } from './utils/constants';
@@ -35,7 +38,6 @@ import { utils } from './utils/utils';
 type TYPE_ALL_FILES_IDENTIFIER = '*';
 const ALL_CONTRACTS_IDENTIFIER = '*';
 const ALL_FILES_IDENTIFIER = '*';
-const SOLC_BIN_DIR = path.join(__dirname, '..', '..', 'solc_bin');
 const DEFAULT_CONTRACTS_DIR = path.resolve('contracts');
 const DEFAULT_ARTIFACTS_DIR = path.resolve('artifacts');
 // Solc compiler settings cannot be configured from the commandline.
@@ -82,49 +84,6 @@ export class Compiler {
     private readonly _artifactsDir: string;
     private readonly _solcVersionIfExists: string | undefined;
     private readonly _specifiedContracts: string[] | TYPE_ALL_FILES_IDENTIFIER;
-    private static async _getSolcAsync(
-        solcVersion: string,
-    ): Promise<{ solcInstance: solc.SolcInstance; fullSolcVersion: string }> {
-        const fullSolcVersion = binPaths[solcVersion];
-        if (_.isUndefined(fullSolcVersion)) {
-            throw new Error(`${solcVersion} is not a known compiler version`);
-        }
-        const compilerBinFilename = path.join(SOLC_BIN_DIR, fullSolcVersion);
-        let solcjs: string;
-        if (await fsWrapper.doesFileExistAsync(compilerBinFilename)) {
-            solcjs = (await fsWrapper.readFileAsync(compilerBinFilename)).toString();
-        } else {
-            logUtils.warn(`Downloading ${fullSolcVersion}...`);
-            const url = `${constants.BASE_COMPILER_URL}${fullSolcVersion}`;
-            const response = await fetchAsync(url);
-            const SUCCESS_STATUS = 200;
-            if (response.status !== SUCCESS_STATUS) {
-                throw new Error(`Failed to load ${fullSolcVersion}`);
-            }
-            solcjs = await response.text();
-            await fsWrapper.writeFileAsync(compilerBinFilename, solcjs);
-        }
-        if (solcjs.length === 0) {
-            throw new Error('No compiler available');
-        }
-        const solcInstance = solc.setupMethods(requireFromString(solcjs, compilerBinFilename));
-        return { solcInstance, fullSolcVersion };
-    }
-    private static _addHexPrefixToContractBytecode(compiledContract: solc.StandardContractOutput): void {
-        if (!_.isUndefined(compiledContract.evm)) {
-            if (!_.isUndefined(compiledContract.evm.bytecode) && !_.isUndefined(compiledContract.evm.bytecode.object)) {
-                compiledContract.evm.bytecode.object = ethUtil.addHexPrefix(compiledContract.evm.bytecode.object);
-            }
-            if (
-                !_.isUndefined(compiledContract.evm.deployedBytecode) &&
-                !_.isUndefined(compiledContract.evm.deployedBytecode.object)
-            ) {
-                compiledContract.evm.deployedBytecode.object = ethUtil.addHexPrefix(
-                    compiledContract.evm.deployedBytecode.object,
-                );
-            }
-        }
-    }
     /**
      * Instantiates a new instance of the Compiler class.
      * @param opts Optional compiler options
@@ -158,7 +117,7 @@ export class Compiler {
      */
     public async compileAsync(): Promise<void> {
         await createDirIfDoesNotExistAsync(this._artifactsDir);
-        await createDirIfDoesNotExistAsync(SOLC_BIN_DIR);
+        await createDirIfDoesNotExistAsync(constants.SOLC_BIN_DIR);
         await this._compileContractsAsync(this._getContractNamesToCompile(), true);
     }
     /**
@@ -173,6 +132,54 @@ export class Compiler {
         const promisedOutputs = this._compileContractsAsync(this._getContractNamesToCompile(), false);
         return promisedOutputs;
     }
+    public async watchAsync(): Promise<void> {
+        console.clear(); // tslint:disable-line:no-console
+        logUtils.logWithTime('Starting compilation in watch mode...');
+        const MATCH_NOTHING_REGEX = '^$';
+        const IGNORE_DOT_FILES_REGEX = /(^|[\/\\])\../;
+        // Initially we watch nothing. We'll add the paths later.
+        const watcher = chokidar.watch(MATCH_NOTHING_REGEX, { ignored: IGNORE_DOT_FILES_REGEX });
+        const onFileChangedAsync = async () => {
+            watcher.unwatch('*'); // Stop watching
+            try {
+                await this.compileAsync();
+                logUtils.logWithTime('Found 0 errors. Watching for file changes.');
+            } catch (err) {
+                if (err.typeName === 'CompilationError') {
+                    logUtils.logWithTime(
+                        `Found ${err.errorsCount} ${pluralize('error', err.errorsCount)}. Watching for file changes.`,
+                    );
+                } else {
+                    logUtils.logWithTime('Found errors. Watching for file changes.');
+                }
+            }
+
+            const pathsToWatch = this._getPathsToWatch();
+            watcher.add(pathsToWatch);
+        };
+        await onFileChangedAsync();
+        watcher.on('change', (changedFilePath: string) => {
+            console.clear(); // tslint:disable-line:no-console
+            logUtils.logWithTime('File change detected. Starting incremental compilation...');
+            // NOTE: We can't await it here because that's a callback.
+            // Instead we stop watching inside of it and start it again when we're finished.
+            onFileChangedAsync(); // tslint:disable-line no-floating-promises
+        });
+    }
+    private _getPathsToWatch(): string[] {
+        const contractNames = this._getContractNamesToCompile();
+        const spyResolver = new SpyResolver(this._resolver);
+        for (const contractName of contractNames) {
+            const contractSource = spyResolver.resolve(contractName);
+            // NOTE: We ignore the return value here. We don't want to compute the source tree hash.
+            // We just want to call a SpyResolver on each contracts and it's dependencies and
+            // this is a convenient way to reuse the existing code that does that.
+            // We can then get all the relevant paths from the `spyResolver` below.
+            getSourceTreeHash(spyResolver, contractSource.path);
+        }
+        const pathsToWatch = _.uniq(spyResolver.resolvedContractSources.map(cs => cs.absolutePath));
+        return pathsToWatch;
+    }
     private _getContractNamesToCompile(): string[] {
         let contractNamesToCompile;
         if (this._specifiedContracts === ALL_CONTRACTS_IDENTIFIER) {
@@ -201,12 +208,14 @@ export class Compiler {
 
         for (const contractName of contractNames) {
             const contractSource = this._resolver.resolve(contractName);
+            const sourceTreeHashHex = getSourceTreeHash(
+                this._resolver,
+                path.join(this._contractsDir, contractSource.path),
+            ).toString('hex');
             const contractData = {
                 contractName,
                 currentArtifactIfExists: await getContractArtifactIfExistsAsync(this._artifactsDir, contractName),
-                sourceTreeHashHex: `0x${this._getSourceTreeHash(
-                    path.join(this._contractsDir, contractSource.path),
-                ).toString('hex')}`,
+                sourceTreeHashHex: `0x${sourceTreeHashHex}`,
             };
             if (!this._shouldCompile(contractData)) {
                 continue;
@@ -244,9 +253,8 @@ export class Compiler {
                 }) with Solidity v${solcVersion}...`,
             );
 
-            const { solcInstance, fullSolcVersion } = await Compiler._getSolcAsync(solcVersion);
-
-            const compilerOutput = this._compile(solcInstance, input.standardInput);
+            const { solcInstance, fullSolcVersion } = await getSolcAsync(solcVersion);
+            const compilerOutput = compile(this._resolver, solcInstance, input.standardInput);
             compilerOutputs.push(compilerOutput);
 
             for (const contractPath of input.contractsToCompile) {
@@ -259,7 +267,7 @@ export class Compiler {
                     );
                 }
 
-                Compiler._addHexPrefixToContractBytecode(compiledContract);
+                addHexPrefixToContractBytecode(compiledContract);
 
                 if (shouldPersist) {
                     await this._persistCompiledContractAsync(
@@ -298,10 +306,14 @@ export class Compiler {
         const compiledContract = compilerOutput.contracts[contractPath][contractName];
 
         // need to gather sourceCodes for this artifact, but compilerOutput.sources (the list of contract modules)
-        // contains listings for for every contract compiled during the compiler invocation that compiled the contract
+        // contains listings for every contract compiled during the compiler invocation that compiled the contract
         // to be persisted, which could include many that are irrelevant to the contract at hand.  So, gather up only
         // the relevant sources:
-        const { sourceCodes, sources } = this._getSourcesWithDependencies(contractPath, compilerOutput.sources);
+        const { sourceCodes, sources } = getSourcesWithDependencies(
+            this._resolver,
+            contractPath,
+            compilerOutput.sources,
+        );
 
         const contractVersion: ContractVersionData = {
             compilerOutput: compiledContract,
@@ -336,130 +348,4 @@ export class Compiler {
         await fsWrapper.writeFileAsync(currentArtifactPath, artifactString);
         logUtils.warn(`${contractName} artifact saved!`);
     }
-    /**
-     * For the given @param contractPath, populates JSON objects to be used in the ContractVersionData interface's
-     * properties `sources` (source code file names mapped to ID numbers) and `sourceCodes` (source code content of
-     * contracts) for that contract.  The source code pointed to by contractPath is read and parsed directly (via
-     * `this._resolver.resolve().source`), as are its imports, recursively.  The ID numbers for @return `sources` are
-     * taken from the corresponding ID's in @param fullSources, and the content for @return sourceCodes is read from
-     * disk (via the aforementioned `resolver.source`).
-     */
-    private _getSourcesWithDependencies(
-        contractPath: string,
-        fullSources: { [sourceName: string]: { id: number } },
-    ): { sourceCodes: { [sourceName: string]: string }; sources: { [sourceName: string]: { id: number } } } {
-        const sources = { [contractPath]: { id: fullSources[contractPath].id } };
-        const sourceCodes = { [contractPath]: this._resolver.resolve(contractPath).source };
-        this._recursivelyGatherDependencySources(
-            contractPath,
-            sourceCodes[contractPath],
-            fullSources,
-            sources,
-            sourceCodes,
-        );
-        return { sourceCodes, sources };
-    }
-    private _recursivelyGatherDependencySources(
-        contractPath: string,
-        contractSource: string,
-        fullSources: { [sourceName: string]: { id: number } },
-        sourcesToAppendTo: { [sourceName: string]: { id: number } },
-        sourceCodesToAppendTo: { [sourceName: string]: string },
-    ): void {
-        const importStatementMatches = contractSource.match(/\nimport[^;]*;/g);
-        if (importStatementMatches === null) {
-            return;
-        }
-        for (const importStatementMatch of importStatementMatches) {
-            const importPathMatches = importStatementMatch.match(/\"([^\"]*)\"/);
-            if (importPathMatches === null || importPathMatches.length === 0) {
-                continue;
-            }
-
-            let importPath = importPathMatches[1];
-            // HACK(ablrow): We have, e.g.:
-            //
-            //      importPath   = "../../utils/LibBytes/LibBytes.sol"
-            //      contractPath = "2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol"
-            //
-            // Resolver doesn't understand "../" so we want to pass
-            // "2.0.0/utils/LibBytes/LibBytes.sol" to resolver.
-            //
-            // This hack involves using path.resolve. But path.resolve returns
-            // absolute directories by default. We trick it into thinking that
-            // contractPath is a root directory by prepending a '/' and then
-            // removing the '/' the end.
-            //
-            //      path.resolve("/a/b/c", ""../../d/e") === "/a/d/e"
-            //
-            const lastPathSeparatorPos = contractPath.lastIndexOf('/');
-            const contractFolder = lastPathSeparatorPos === -1 ? '' : contractPath.slice(0, lastPathSeparatorPos + 1);
-            if (importPath.startsWith('.')) {
-                /**
-                 * Some imports path are relative ("../Token.sol", "./Wallet.sol")
-                 * while others are absolute ("Token.sol", "@0x/contracts/Wallet.sol")
-                 * And we need to append the base path for relative imports.
-                 */
-                importPath = path.resolve(`/${contractFolder}`, importPath).replace('/', '');
-            }
-
-            if (_.isUndefined(sourcesToAppendTo[importPath])) {
-                sourcesToAppendTo[importPath] = { id: fullSources[importPath].id };
-                sourceCodesToAppendTo[importPath] = this._resolver.resolve(importPath).source;
-
-                this._recursivelyGatherDependencySources(
-                    importPath,
-                    this._resolver.resolve(importPath).source,
-                    fullSources,
-                    sourcesToAppendTo,
-                    sourceCodesToAppendTo,
-                );
-            }
-        }
-    }
-    private _compile(solcInstance: solc.SolcInstance, standardInput: solc.StandardInput): solc.StandardOutput {
-        const compiled: solc.StandardOutput = JSON.parse(
-            solcInstance.compileStandardWrapper(JSON.stringify(standardInput), importPath => {
-                const sourceCodeIfExists = this._resolver.resolve(importPath);
-                return { contents: sourceCodeIfExists.source };
-            }),
-        );
-        if (!_.isUndefined(compiled.errors)) {
-            const SOLIDITY_WARNING = 'warning';
-            const errors = _.filter(compiled.errors, entry => entry.severity !== SOLIDITY_WARNING);
-            const warnings = _.filter(compiled.errors, entry => entry.severity === SOLIDITY_WARNING);
-            if (!_.isEmpty(errors)) {
-                errors.forEach(error => {
-                    const normalizedErrMsg = getNormalizedErrMsg(error.formattedMessage || error.message);
-                    logUtils.warn(chalk.red(normalizedErrMsg));
-                });
-                throw new Error('Compilation errors encountered');
-            } else {
-                warnings.forEach(warning => {
-                    const normalizedWarningMsg = getNormalizedErrMsg(warning.formattedMessage || warning.message);
-                    logUtils.warn(chalk.yellow(normalizedWarningMsg));
-                });
-            }
-        }
-        return compiled;
-    }
-    /**
-     * Gets the source tree hash for a file and its dependencies.
-     * @param fileName Name of contract file.
-     */
-    private _getSourceTreeHash(importPath: string): Buffer {
-        const contractSource = this._resolver.resolve(importPath);
-        const dependencies = parseDependencies(contractSource);
-        const sourceHash = ethUtil.sha3(contractSource.source);
-        if (dependencies.length === 0) {
-            return sourceHash;
-        } else {
-            const dependencySourceTreeHashes = _.map(dependencies, (dependency: string) =>
-                this._getSourceTreeHash(dependency),
-            );
-            const sourceTreeHashesBuffer = Buffer.concat([sourceHash, ...dependencySourceTreeHashes]);
-            const sourceTreeHash = ethUtil.sha3(sourceTreeHashesBuffer);
-            return sourceTreeHash;
-        }
-    }
 }
diff --git a/packages/sol-compiler/src/utils/compiler.ts b/packages/sol-compiler/src/utils/compiler.ts
index cda67a414..db308f2b5 100644
--- a/packages/sol-compiler/src/utils/compiler.ts
+++ b/packages/sol-compiler/src/utils/compiler.ts
@@ -1,10 +1,18 @@
-import { ContractSource } from '@0x/sol-resolver';
-import { logUtils } from '@0x/utils';
+import { ContractSource, Resolver } from '@0x/sol-resolver';
+import { fetchAsync, logUtils } from '@0x/utils';
+import chalk from 'chalk';
 import { ContractArtifact } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
 import * as _ from 'lodash';
 import * as path from 'path';
+import * as requireFromString from 'require-from-string';
+import * as solc from 'solc';
 
+import { binPaths } from '../solc/bin_paths';
+
+import { constants } from './constants';
 import { fsWrapper } from './fs_wrapper';
+import { CompilationError } from './types';
 
 /**
  * Gets contract data on network or returns if an artifact does not exist.
@@ -106,3 +114,208 @@ export function parseDependencies(contractSource: ContractSource): string[] {
     });
     return dependencies;
 }
+
+/**
+ * Compiles the contracts and prints errors/warnings
+ * @param resolver Resolver
+ * @param solcInstance Instance of a solc compiler
+ * @param standardInput Solidity standard JSON input
+ */
+export function compile(
+    resolver: Resolver,
+    solcInstance: solc.SolcInstance,
+    standardInput: solc.StandardInput,
+): solc.StandardOutput {
+    const standardInputStr = JSON.stringify(standardInput);
+    const standardOutputStr = solcInstance.compileStandardWrapper(standardInputStr, importPath => {
+        const sourceCodeIfExists = resolver.resolve(importPath);
+        return { contents: sourceCodeIfExists.source };
+    });
+    const compiled: solc.StandardOutput = JSON.parse(standardOutputStr);
+    if (!_.isUndefined(compiled.errors)) {
+        printCompilationErrorsAndWarnings(compiled.errors);
+    }
+    return compiled;
+}
+/**
+ * Separates errors from warnings, formats the messages and prints them. Throws if there is any compilation error (not warning).
+ * @param solcErrors The errors field of standard JSON output that contains errors and warnings.
+ */
+function printCompilationErrorsAndWarnings(solcErrors: solc.SolcError[]): void {
+    const SOLIDITY_WARNING = 'warning';
+    const errors = _.filter(solcErrors, entry => entry.severity !== SOLIDITY_WARNING);
+    const warnings = _.filter(solcErrors, entry => entry.severity === SOLIDITY_WARNING);
+    if (!_.isEmpty(errors)) {
+        errors.forEach(error => {
+            const normalizedErrMsg = getNormalizedErrMsg(error.formattedMessage || error.message);
+            logUtils.log(chalk.red('error'), normalizedErrMsg);
+        });
+        throw new CompilationError(errors.length);
+    } else {
+        warnings.forEach(warning => {
+            const normalizedWarningMsg = getNormalizedErrMsg(warning.formattedMessage || warning.message);
+            logUtils.log(chalk.yellow('warning'), normalizedWarningMsg);
+        });
+    }
+}
+
+/**
+ * Gets the source tree hash for a file and its dependencies.
+ * @param fileName Name of contract file.
+ */
+export function getSourceTreeHash(resolver: Resolver, importPath: string): Buffer {
+    const contractSource = resolver.resolve(importPath);
+    const dependencies = parseDependencies(contractSource);
+    const sourceHash = ethUtil.sha3(contractSource.source);
+    if (dependencies.length === 0) {
+        return sourceHash;
+    } else {
+        const dependencySourceTreeHashes = _.map(dependencies, (dependency: string) =>
+            getSourceTreeHash(resolver, dependency),
+        );
+        const sourceTreeHashesBuffer = Buffer.concat([sourceHash, ...dependencySourceTreeHashes]);
+        const sourceTreeHash = ethUtil.sha3(sourceTreeHashesBuffer);
+        return sourceTreeHash;
+    }
+}
+
+/**
+ * For the given @param contractPath, populates JSON objects to be used in the ContractVersionData interface's
+ * properties `sources` (source code file names mapped to ID numbers) and `sourceCodes` (source code content of
+ * contracts) for that contract.  The source code pointed to by contractPath is read and parsed directly (via
+ * `resolver.resolve().source`), as are its imports, recursively.  The ID numbers for @return `sources` are
+ * taken from the corresponding ID's in @param fullSources, and the content for @return sourceCodes is read from
+ * disk (via the aforementioned `resolver.source`).
+ */
+export function getSourcesWithDependencies(
+    resolver: Resolver,
+    contractPath: string,
+    fullSources: { [sourceName: string]: { id: number } },
+): { sourceCodes: { [sourceName: string]: string }; sources: { [sourceName: string]: { id: number } } } {
+    const sources = { [contractPath]: { id: fullSources[contractPath].id } };
+    const sourceCodes = { [contractPath]: resolver.resolve(contractPath).source };
+    recursivelyGatherDependencySources(
+        resolver,
+        contractPath,
+        sourceCodes[contractPath],
+        fullSources,
+        sources,
+        sourceCodes,
+    );
+    return { sourceCodes, sources };
+}
+
+function recursivelyGatherDependencySources(
+    resolver: Resolver,
+    contractPath: string,
+    contractSource: string,
+    fullSources: { [sourceName: string]: { id: number } },
+    sourcesToAppendTo: { [sourceName: string]: { id: number } },
+    sourceCodesToAppendTo: { [sourceName: string]: string },
+): void {
+    const importStatementMatches = contractSource.match(/\nimport[^;]*;/g);
+    if (importStatementMatches === null) {
+        return;
+    }
+    for (const importStatementMatch of importStatementMatches) {
+        const importPathMatches = importStatementMatch.match(/\"([^\"]*)\"/);
+        if (importPathMatches === null || importPathMatches.length === 0) {
+            continue;
+        }
+
+        let importPath = importPathMatches[1];
+        // HACK(albrow): We have, e.g.:
+        //
+        //      importPath   = "../../utils/LibBytes/LibBytes.sol"
+        //      contractPath = "2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol"
+        //
+        // Resolver doesn't understand "../" so we want to pass
+        // "2.0.0/utils/LibBytes/LibBytes.sol" to resolver.
+        //
+        // This hack involves using path.resolve. But path.resolve returns
+        // absolute directories by default. We trick it into thinking that
+        // contractPath is a root directory by prepending a '/' and then
+        // removing the '/' the end.
+        //
+        //      path.resolve("/a/b/c", ""../../d/e") === "/a/d/e"
+        //
+        const lastPathSeparatorPos = contractPath.lastIndexOf('/');
+        const contractFolder = lastPathSeparatorPos === -1 ? '' : contractPath.slice(0, lastPathSeparatorPos + 1);
+        if (importPath.startsWith('.')) {
+            /**
+             * Some imports path are relative ("../Token.sol", "./Wallet.sol")
+             * while others are absolute ("Token.sol", "@0x/contracts/Wallet.sol")
+             * And we need to append the base path for relative imports.
+             */
+            importPath = path.resolve(`/${contractFolder}`, importPath).replace('/', '');
+        }
+
+        if (_.isUndefined(sourcesToAppendTo[importPath])) {
+            sourcesToAppendTo[importPath] = { id: fullSources[importPath].id };
+            sourceCodesToAppendTo[importPath] = resolver.resolve(importPath).source;
+
+            recursivelyGatherDependencySources(
+                resolver,
+                importPath,
+                resolver.resolve(importPath).source,
+                fullSources,
+                sourcesToAppendTo,
+                sourceCodesToAppendTo,
+            );
+        }
+    }
+}
+
+/**
+ * Gets the solidity compiler instance and full version name. If the compiler is already cached - gets it from FS,
+ * otherwise - fetches it and caches it.
+ * @param solcVersion The compiler version. e.g. 0.5.0
+ */
+export async function getSolcAsync(
+    solcVersion: string,
+): Promise<{ solcInstance: solc.SolcInstance; fullSolcVersion: string }> {
+    const fullSolcVersion = binPaths[solcVersion];
+    if (_.isUndefined(fullSolcVersion)) {
+        throw new Error(`${solcVersion} is not a known compiler version`);
+    }
+    const compilerBinFilename = path.join(constants.SOLC_BIN_DIR, fullSolcVersion);
+    let solcjs: string;
+    if (await fsWrapper.doesFileExistAsync(compilerBinFilename)) {
+        solcjs = (await fsWrapper.readFileAsync(compilerBinFilename)).toString();
+    } else {
+        logUtils.warn(`Downloading ${fullSolcVersion}...`);
+        const url = `${constants.BASE_COMPILER_URL}${fullSolcVersion}`;
+        const response = await fetchAsync(url);
+        const SUCCESS_STATUS = 200;
+        if (response.status !== SUCCESS_STATUS) {
+            throw new Error(`Failed to load ${fullSolcVersion}`);
+        }
+        solcjs = await response.text();
+        await fsWrapper.writeFileAsync(compilerBinFilename, solcjs);
+    }
+    if (solcjs.length === 0) {
+        throw new Error('No compiler available');
+    }
+    const solcInstance = solc.setupMethods(requireFromString(solcjs, compilerBinFilename));
+    return { solcInstance, fullSolcVersion };
+}
+
+/**
+ * Solidity compiler emits the bytecode without a 0x prefix for a hex. This function fixes it if bytecode is present.
+ * @param compiledContract The standard JSON output section for a contract. Geth modified in place.
+ */
+export function addHexPrefixToContractBytecode(compiledContract: solc.StandardContractOutput): void {
+    if (!_.isUndefined(compiledContract.evm)) {
+        if (!_.isUndefined(compiledContract.evm.bytecode) && !_.isUndefined(compiledContract.evm.bytecode.object)) {
+            compiledContract.evm.bytecode.object = ethUtil.addHexPrefix(compiledContract.evm.bytecode.object);
+        }
+        if (
+            !_.isUndefined(compiledContract.evm.deployedBytecode) &&
+            !_.isUndefined(compiledContract.evm.deployedBytecode.object)
+        ) {
+            compiledContract.evm.deployedBytecode.object = ethUtil.addHexPrefix(
+                compiledContract.evm.deployedBytecode.object,
+            );
+        }
+    }
+}
diff --git a/packages/sol-compiler/src/utils/constants.ts b/packages/sol-compiler/src/utils/constants.ts
index df2ddb3b2..433897f8a 100644
--- a/packages/sol-compiler/src/utils/constants.ts
+++ b/packages/sol-compiler/src/utils/constants.ts
@@ -1,5 +1,8 @@
+import * as path from 'path';
+
 export const constants = {
     SOLIDITY_FILE_EXTENSION: '.sol',
     BASE_COMPILER_URL: 'https://ethereum.github.io/solc-bin/bin/',
     LATEST_ARTIFACT_VERSION: '2.0.0',
+    SOLC_BIN_DIR: path.join(__dirname, '..', '..', 'solc_bin'),
 };
diff --git a/packages/sol-compiler/src/utils/types.ts b/packages/sol-compiler/src/utils/types.ts
index b211cfcbc..64328899d 100644
--- a/packages/sol-compiler/src/utils/types.ts
+++ b/packages/sol-compiler/src/utils/types.ts
@@ -29,3 +29,12 @@ export interface Token {
 }
 
 export type DoneCallback = (err?: Error) => void;
+
+export class CompilationError extends Error {
+    public errorsCount: number;
+    public typeName = 'CompilationError';
+    constructor(errorsCount: number) {
+        super('Compilation errors encountered');
+        this.errorsCount = errorsCount;
+    }
+}
diff --git a/packages/sol-compiler/test/compiler_utils_test.ts b/packages/sol-compiler/test/compiler_utils_test.ts
index 4fe7b994e..b8c18110c 100644
--- a/packages/sol-compiler/test/compiler_utils_test.ts
+++ b/packages/sol-compiler/test/compiler_utils_test.ts
@@ -52,7 +52,7 @@ describe('Compiler utils', () => {
             const source = await fsWrapper.readFileAsync(path, {
                 encoding: 'utf8',
             });
-            const dependencies = parseDependencies({ source, path });
+            const dependencies = parseDependencies({ source, path, absolutePath: path });
             const expectedDependencies = [
                 'zeppelin-solidity/contracts/token/ERC20/ERC20.sol',
                 'packages/sol-compiler/lib/test/fixtures/contracts/TokenTransferProxy.sol',
@@ -68,7 +68,7 @@ describe('Compiler utils', () => {
             const source = await fsWrapper.readFileAsync(path, {
                 encoding: 'utf8',
             });
-            expect(parseDependencies({ source, path })).to.be.deep.equal([
+            expect(parseDependencies({ source, path, absolutePath: path })).to.be.deep.equal([
                 'zeppelin-solidity/contracts/ownership/Ownable.sol',
                 'zeppelin-solidity/contracts/token/ERC20/ERC20.sol',
             ]);
@@ -77,7 +77,7 @@ describe('Compiler utils', () => {
         it.skip('correctly parses commented out dependencies', async () => {
             const path = '';
             const source = `// import "./TokenTransferProxy.sol";`;
-            expect(parseDependencies({ path, source })).to.be.deep.equal([]);
+            expect(parseDependencies({ path, source, absolutePath: path })).to.be.deep.equal([]);
         });
     });
 });