Accept underscores in module path (#58)

* Accept underscores in module path (with a test)

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/.gitignore

@@ -0,0 +1,11 @@
+npm-debug.log
+.merlin
+yarn-error.log
+node_modules
+node_modules/
+_build
+_release
+_esy/
+y.install
+.DS_Store
+*.install

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/dune

@@ -0,0 +1 @@
+(dirs (:standard \ node_modules \ _esy))

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/dune-project

@@ -0,0 +1,2 @@
+(lang dune 1.6)
+ (name pesy-c-stubs)

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/executable/PesyNpmApp.re

@@ -0,0 +1,2 @@
+Library.Util.foo();
+Bar.bar();

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/lib_foo/Util.re

@@ -0,0 +1 @@
+let foo = () => print_endline("Hello");

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/lib_foo/foo/bar/Index.re

@@ -0,0 +1 @@
+let bar = () => print_endline("in bar");

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/package.json

@@ -0,0 +1,49 @@
+{
+  "name": "pesy-npm",
+  "version": "0.0.0",
+  "description": "My Project",
+  "esy": {
+    "build": "dune build -p #{self.name}",
+    "release": {
+      "releasedBinaries": [
+        "PesyNpmApp.exe"
+      ]
+    }
+  },
+  "buildDirs": {
+    "test": {
+      "imports": [
+        "Library = require('pesy-npm/lib_foo')"
+      ],
+      "bin": "TestPesyNpm.re"
+    },
+    "lib_foo": {},
+    "lib_foo/foo/bar": {},
+    "executable": {
+      "imports": [
+        "Bar = require('pesy-npm/lib_foo/foo/bar')",
+        "Library = require('pesy-npm/lib_foo')"
+      ],
+      "bin": {
+        "pesy-npm-app.exe": "PesyNpmApp.re"
+      }
+    }
+  },
+  "scripts": {
+    "test": "esy b dune runtest"
+  },
+  "dependencies": {
+    "ocaml": "4.7.x",
+    "@opam/dune": ">=1.6.0",
+    "@esy-ocaml/reason": "*",
+    "refmterr": "*",
+    "pesy": "*",
+    "refmterr": "*"
+  },
+  "devDependencies": {
+    "@opam/merlin": "*"
+  },
+  "resolutions": {
+    "pesy": "<RESOLUTION_LINK>"
+  }
+}

e2e-tests/pesy-configure-test-projects/pesy-npm-with-underscore/test/TestPesyNpm.re

@@ -0,0 +1,2 @@
+Library.Util.foo();
+print_endline("Add Your Test Cases Here");

lib/Lexer.mll

@@ -10,6 +10,6 @@ rule read = parse
 | "require"  { REQUIRE }
 | ['\'']      { SQUOTE }
 | ['A' - 'Z' ] [ 'A' - 'Z' 'a' - 'z' '_'] * as lxm { MODULE_NAME(lxm)  }
-| ['@'] ? ['a'-'z' '.' '/' '-' '0'-'9'] + as lxm { MODULE_PATH(lxm)  }
+| ['@'] ? ['a'-'z' '.' '/' '-' '0'-'9' '_'] + as lxm { MODULE_PATH(lxm)  }
 | ['\n']     {EOL}
 | eof      {EOF}