Merge pull request ethereum#2398 from ethereum/compiler_from_pragma

pickup compiler version from pragma

src/app/tabs/compileTab/compilerContainer.js

@@ -32,6 +32,9 @@ class CompilerContainer {
    * Update the compilation button with the name of the current file
    */
   set currentFile (name = '') {
+    if (name && name !== '') {
+      this._setCompilerVersionFromPragma(name)
+    }
     if (!this._view.compilationButton) return
     const button = this.compilationButton(name.split('/').pop())
     yo.update(this._view.compilationButton, button)
@@ -113,6 +116,23 @@ class CompilerContainer {
     return el
   }
 
+  _setCompilerVersionFromPragma (filename) {
+    this.compileTabLogic.fileManager.getFile(filename).then(data => {
+      const pragmaArr = data.match(/(pragma solidity (.+?);)/g)
+      if (pragmaArr && pragmaArr.length === 1) {
+        const pragmaStr = pragmaArr[0].replace('pragma solidity', '').trim()
+        const pragma = pragmaStr.substring(0, pragmaStr.length - 1)
+        const fixedVersions = this.data.allversions.filter(obj => !obj.prerelease).map(obj => obj.version)
+        const compilerToLoad = semver.maxSatisfying(fixedVersions, pragma)
+        const compilerPath = this.data.allversions.filter(obj => !obj.prerelease && obj.version === compilerToLoad)[0].path
+        if (this.data.selectedVersion !== compilerPath) {
+          this.data.selectedVersion = compilerPath
+          this._updateVersionSelector()
+        }
+      }
+    })
+  }
+
   _retrieveVersion () {
     let version = this._view.versionSelector.value
     return version.substring(9, version.length)
@@ -243,6 +263,9 @@ class CompilerContainer {
 
   compile (event) {
     if (this.config.get('currentFile')) {
+      if (!this.data.selectedVersion.includes('nightly')) {
+        this._setCompilerVersionFromPragma(this.config.get('currentFile'))
+      }
       this.compileTabLogic.runCompiler()
     }
   }