[oil-language] Implement 1_000_000 syntax

Addresses oils-for-unix#957.

doc/oil-language-tour.md

@@ -513,7 +513,7 @@ If statements have optional `elif` and `else` clauses:
 
     if test --file foo {
       echo 'foo is a file'
-      rm --verbose foo           # delete it
+      rm --verbose foo     # delete it
     } elif test --dir foo {
       echo 'foo is a directory'
     } else {
@@ -522,7 +522,7 @@ If statements have optional `elif` and `else` clauses:
 
 If statements are also used for **error handling**:
 
-    if ! cp foo /tmp {           # The word ! inverts the exit status
+    if ! cp foo /tmp {     # The word ! inverts the exit status
       echo 'error copying'
     }
 
@@ -540,7 +540,7 @@ rather than a command:
     }
 
     var done = false
-    if (not done) {              # negate with 'not' operator (contrast with !)
+    if (not done) {        # negate with 'not' operator (contrast with !)
       echo "we aren't done"
     }
 
@@ -652,11 +652,11 @@ breaks the rule that types are spelled with capital letters (e.g. `Str`,
 
 There are many ways to write integers:
 
-    #var small, big = 42, 65_536         # TODO: _ not supported yet
-    #echo "$small $big"                  # => 42 65536
+    var small, big = 42, 65_536
+    echo "$small $big"                  # => 42 65536
 
-    var hex, octal, binary = 0xFF, 0o755, 0b0101
-    echo "$hex $octal $binary"           # => 255 493 5
+    var hex, octal, binary = 0x0001_0000, 0o755, 0b0001_0101
+    echo "$hex $octal $binary"           # => 65536 493 21
 
 <!--
 TODO: not supported yet

oil_lang/expr_eval.py

@@ -203,17 +203,21 @@ def EvalExpr(self, node):
     if node.tag == expr_e.Const:
       id_ = node.c.id
 
+      # Remove underscores from 1_000_000.  The lexer is responsible for
+      # validation.
+      c = node.c.val.replace('_', '')
+
       if id_ == Id.Expr_DecInt:
-        return int(node.c.val)
+        return int(c)
       elif id_ == Id.Expr_BinInt:
-        return int(node.c.val, 2)
+        return int(c, 2)
       elif id_ == Id.Expr_OctInt:
-        return int(node.c.val, 8)
+        return int(c, 8)
       elif id_ == Id.Expr_HexInt:
-        return int(node.c.val, 16)
+        return int(c, 16)
 
       elif id_ == Id.Expr_Float:
-        return float(node.c.val)
+        return float(c)
 
       elif id_ == Id.Expr_Null:
         return None

spec/oil-expr.test.sh

@@ -305,6 +305,49 @@ echo $d $b $o $h
 123 3 83 255
 ## END
 
+#### Integer literals with underscores
+const dec = 65_536
+const bin = 0b0001_0101
+const oct = 0o001_755
+const hex = 0x0001_000f
+
+echo SHELL
+echo $dec
+echo $bin
+echo $oct
+echo $hex
+const x = 1_1 + 0b1_1 + 0o1_1 + 0x1_1
+echo sum $x
+
+echo ---
+echo PYTHON
+
+python3 -c '
+print(65_536)
+print(0b0001_0101)
+print(0o001_755)
+print(0x0001_000f)
+
+# Weird syntax
+print("sum", 1_1 + 0b1_1 + 0o1_1 + 0x1_1)
+'
+
+## STDOUT:
+SHELL
+65536
+21
+1005
+65551
+sum 40
+---
+PYTHON
+65536
+21
+1005
+65551
+sum 40
+## END
+
 #### Float Literals
 shopt -s oil:basic
 # 1+2 2.3