implement array slicing

google · Feb 25, 2016 · ed6a951 · ed6a951
1 parent 709da7f
commit ed6a951
Show file tree

Hide file tree

Showing 12 changed files with 280 additions and 42 deletions.
diff --git a/core/ast.h b/core/ast.h
@@ -309,11 +309,17 @@ struct Importstr : public AST {
  * One of index and id will be nullptr before desugaring.  After desugaring id will be nullptr.
  */
 struct Index : public AST {
+    bool isSlice;
     AST *target;
     AST *index;
+    AST *end;
+    AST *step;
     const Identifier *id;
     Index(const LocationRange &lr, AST *target, AST *index, const Identifier *id)
-      : AST(lr, AST_INDEX), target(target), index(index), id(id)
+      : AST(lr, AST_INDEX), isSlice(false), target(target), index(index), end(nullptr), step(nullptr), id(id)
+    { }
+    Index(const LocationRange &lr, AST *target, AST *index, AST *end, AST *step)
+      : AST(lr, AST_INDEX), isSlice(true), target(target), index(index), end(end), step(step), id(nullptr)
     { }
 };
 

diff --git a/core/desugaring.cpp b/core/desugaring.cpp
@@ -21,7 +21,7 @@ limitations under the License.
 #include "parser.h"
 
 static LocationRange E;  // Empty.
-    
+
 static unsigned long max_builtin = 24;
 BuiltinDecl jsonnet_builtin_decl(unsigned long builtin)
 {
@@ -438,7 +438,7 @@ class Desugarer {
                     } break;
                 }
             }
-                    
+
             ast_ = in;
 
         } else if (auto *ast = dynamic_cast<Assert*>(ast_)) {
@@ -511,13 +511,44 @@ class Desugarer {
             // Nothing to do.
 
         } else if (auto *ast = dynamic_cast<Index*>(ast_)) {
-            desugar(ast->target, obj_level);
-            if (ast->id != nullptr) {
-                assert(ast->index == nullptr);
-                ast->index = str(ast->id->name);
-                ast->id = nullptr;
+            if (ast->isSlice) {
+                if (ast->index == nullptr)
+                    ast->index = make<LiteralNull>(ast->location);
+                desugar(ast->index, obj_level);
+
+                if (ast->end == nullptr)
+                    ast->end = make<LiteralNull>(ast->location);
+                desugar(ast->end, obj_level);
+
+                if (ast->step == nullptr)
+                    ast->step = make<LiteralNull>(ast->location);
+                desugar(ast->step, obj_level);
+
+                ast_ = make<Apply>(
+                    ast->location,
+                    make<Index>(
+                        E,
+                        std(),
+                        str(U"slice"),
+                        nullptr),
+                    std::vector<AST*>{
+                        ast->target,
+                        ast->index,
+                        ast->end,
+                        ast->step,
+                    },
+                    false,
+                    false
+                );
+            } else {
+                desugar(ast->target, obj_level);
+                if (ast->id != nullptr) {
+                    assert(ast->index == nullptr);
+                    ast->index = str(ast->id->name);
+                    ast->id = nullptr;
+                }
+                desugar(ast->index, obj_level);
             }
-            desugar(ast->index, obj_level);
 
         } else if (auto *ast = dynamic_cast<Local*>(ast_)) {
             for (auto &bind: ast->binds)

diff --git a/core/parser.cpp b/core/parser.cpp
@@ -526,6 +526,10 @@ namespace {
             return tok;
         }
 
+        void push(Token tok) {
+            tokens.push_front(tok);
+        }
+
         Token peek(void)
         {
             Token tok = tokens.front();
@@ -955,7 +959,7 @@ namespace {
                         }
                     } while (true);
                     return alloc->make<Array>(span(tok, next), elements, got_comma);
-                    
+
                 }
 
                 case Token::PAREN_L: {
@@ -1186,9 +1190,54 @@ namespace {
 
                     Token op = pop();
                     if (op.kind == Token::BRACKET_L) {
-                        AST *index = parse(MAX_PRECEDENCE);
+                        bool is_slice = true;
+                        AST *first = nullptr;
+                        AST *second = nullptr;
+                        AST *third = nullptr;
+
+                        if (peek().kind == Token::BRACKET_R)
+                            throw unexpected(pop(), "parsing index");
+
+                        if (peek().data == "::") {
+                            Token joined = popExpect(Token::OPERATOR, "::");
+                            Token delim = Token(Token::OPERATOR, joined.fodder, ":",
+                                joined.stringBlockIndent, joined.stringBlockTermIndent,
+                                joined.location);
+                            push(delim);
+                            push(delim);
+                        }
+
+                        if (peek().data != ":")
+                            first = parse(MAX_PRECEDENCE);
+
+                        if (peek().kind != Token::BRACKET_R) {
+
+                            Token delim = pop();
+                            if (delim.data != ":")
+                                throw unexpected(delim, "parsing slice");
+
+                            if (peek().data != ":" &&
+                                peek().kind != Token::BRACKET_R)
+                                second = parse(MAX_PRECEDENCE);
+
+                            if (peek().kind != Token::BRACKET_R) {
+
+                                Token delim = pop();
+                                if (delim.data != ":")
+                                    throw unexpected(delim, "parsing slice");
+
+                                if (peek().kind != Token::BRACKET_R)
+                                    third= parse(MAX_PRECEDENCE);
+                            }
+                        } else {
+                            is_slice = false;
+                        }
                         Token end = popExpect(Token::BRACKET_R);
-                        lhs = alloc->make<Index>(span(begin, end), lhs, index, nullptr);
+
+                        if (is_slice)
+                            lhs = alloc->make<Index>(span(begin, end), lhs, first, second, third);
+                        else
+                            lhs = alloc->make<Index>(span(begin, end), lhs, first, nullptr);
 
                     } else if (op.kind == Token::DOT) {
                         Token field_id = popExpect(Token::IDENTIFIER);

diff --git a/stdlib/std.jsonnet b/stdlib/std.jsonnet
@@ -88,6 +88,41 @@ limitations under the License.
     range(from, to)::
         std.makeArray(to - from + 1, function(i) i + from),
 
+    slice(indexable, index, end, step)::
+        if (index != null && index < 0) || (end != null && end < 0) || (step != null && step < 0) then
+            error("got [%s:%s:%s] but negative index, end, and steps are not implemented" % [index, end, step] )
+        else if std.type(indexable) != "string" && std.type(indexable) != "array" then
+            error("std.slice accepts a string or an array, but got: %s" % std.type(indexable))
+        else
+            local invar =
+                // loop invariant with defaults applied
+                {
+                    indexable: indexable,
+                    index:
+                        if index == null then 0
+                        else index,
+                    end:
+                        if end == null then std.length(indexable)
+                        else end,
+                    step:
+                        if step == null then 1
+                        else step,
+                    length: std.length(indexable),
+                    type: std.type(indexable)
+                };
+            local build(slice, cur) =
+                if cur >= invar.end || cur >= invar.length then
+                    slice
+                else
+                    build(
+                        if invar.type == "string" then
+                            slice + invar.indexable[cur]
+                        else
+                            slice + [ invar.indexable[cur] ],
+                        cur + invar.step
+                    ) tailstrict;
+            build(if invar.type == "string" then "" else [], invar.index),
+
     count(arr, x):: std.length(std.filter(function(v) v==x, arr)),
 
     mod(a, b)::
@@ -260,7 +295,7 @@ limitations under the License.
                     { i: i + 1, v: "%", caps: false }
                 else
                     error "Unrecognised conversion type: " + c;
-                    
+
 
         // Parsed initial %, now the rest.
         local parse_code(str, i) =
@@ -658,10 +693,10 @@ limitations under the License.
                 else
                     ch;
         "\"%s\"" % std.foldl(function(a, b) a + trans(b), std.stringChars(str), ""),
-    
+
     escapeStringPython(str)::
         std.escapeStringJson(str),
-        
+
     escapeStringBash(str_)::
         local str = std.toString(str_);
         local trans(ch) =
@@ -754,7 +789,7 @@ limitations under the License.
         else
             aux(bytes, 0, ""),
 
-    
+
     base64DecodeBytes(str)::
         if std.length(str) % 4 != 0 then
             error "Not a base64 encoded string \"%s\"" % str

diff --git a/test_suite/error.equality_function.jsonnet.golden b/test_suite/error.equality_function.jsonnet.golden
@@ -1,3 +1,3 @@
 RUNTIME ERROR: Cannot test equality of functions
-	std.jsonnet:913:17-41	function <anonymous>
+	std.jsonnet:948:17-41	function <anonymous>
 	error.equality_function.jsonnet:17:1-31	
diff --git a/test_suite/error.inside_equals_array.jsonnet.golden b/test_suite/error.inside_equals_array.jsonnet.golden
@@ -1,11 +1,11 @@
 RUNTIME ERROR: foobar
 	error.inside_equals_array.jsonnet:18:18-31	thunk <array_element>
-	std.jsonnet:893:41-44	thunk <b>
-	std.jsonnet:881:29	thunk <x>
-	std.jsonnet:881:20-30	thunk <tb>
-	std.jsonnet:882:37-38	thunk <b>
-	std.jsonnet:882:13-39	function <anonymous>
-	std.jsonnet:893:33-44	function <aux>
-	std.jsonnet:896:29-44	function <aux>
-	std.jsonnet:897:21-32	function <anonymous>
+	std.jsonnet:928:41-44	thunk <b>
+	std.jsonnet:916:29	thunk <x>
+	std.jsonnet:916:20-30	thunk <tb>
+	std.jsonnet:917:37-38	thunk <b>
+	std.jsonnet:917:13-39	function <anonymous>
+	std.jsonnet:928:33-44	function <aux>
+	std.jsonnet:931:29-44	function <aux>
+	std.jsonnet:932:21-32	function <anonymous>
 	error.inside_equals_array.jsonnet:19:1-6	
diff --git a/test_suite/error.inside_equals_object.jsonnet.golden b/test_suite/error.inside_equals_object.jsonnet.golden
@@ -1,11 +1,11 @@
 RUNTIME ERROR: foobar
 	error.inside_equals_object.jsonnet:18:22-35	object <b>
-	std.jsonnet:907:62-65	thunk <b>
-	std.jsonnet:881:29	thunk <x>
-	std.jsonnet:881:20-30	thunk <tb>
-	std.jsonnet:882:37-38	thunk <b>
-	std.jsonnet:882:13-39	function <anonymous>
-	std.jsonnet:907:54-65	function <aux>
-	std.jsonnet:910:29-44	function <aux>
-	std.jsonnet:911:21-32	function <anonymous>
+	std.jsonnet:942:62-65	thunk <b>
+	std.jsonnet:916:29	thunk <x>
+	std.jsonnet:916:20-30	thunk <tb>
+	std.jsonnet:917:37-38	thunk <b>
+	std.jsonnet:917:13-39	function <anonymous>
+	std.jsonnet:942:54-65	function <aux>
+	std.jsonnet:945:29-44	function <aux>
+	std.jsonnet:946:21-32	function <anonymous>
 	error.inside_equals_object.jsonnet:19:1-6	
diff --git a/test_suite/error.invariant.equality.jsonnet.golden b/test_suite/error.invariant.equality.jsonnet.golden
@@ -1,10 +1,10 @@
 RUNTIME ERROR: Object assertion failed.
 	error.invariant.equality.jsonnet:17:10-14	thunk <object_assert>
-	std.jsonnet:907:54-57	thunk <a>
-	std.jsonnet:880:29	thunk <x>
-	std.jsonnet:880:20-30	thunk <ta>
-	std.jsonnet:882:33-34	thunk <a>
-	std.jsonnet:882:13-39	function <anonymous>
-	std.jsonnet:907:54-65	function <aux>
-	std.jsonnet:911:21-32	function <anonymous>
+	std.jsonnet:942:54-57	thunk <a>
+	std.jsonnet:915:29	thunk <x>
+	std.jsonnet:915:20-30	thunk <ta>
+	std.jsonnet:917:33-34	thunk <a>
+	std.jsonnet:917:13-39	function <anonymous>
+	std.jsonnet:942:54-65	function <aux>
+	std.jsonnet:946:21-32	function <anonymous>
 	error.invariant.equality.jsonnet:17:1-32	
diff --git a/test_suite/error.sanity.jsonnet.golden b/test_suite/error.sanity.jsonnet.golden
@@ -1,3 +1,3 @@
 RUNTIME ERROR: Assertion failed. 1 != 2
-	std.jsonnet:600:13-55	function <anonymous>
+	std.jsonnet:635:13-55	function <anonymous>
 	error.sanity.jsonnet:17:1-21	
diff --git a/test_suite/error.slice_out_of_bounds.sugar.jsonnet.golden b/test_suite/error.slice_out_of_bounds.sugar.jsonnet.golden
@@ -0,0 +1,3 @@
+RUNTIME ERROR: Array bounds error: 6 not within [0, 6)
+	std.jsonnet:92:46-58	thunk <array_element>
+	During manifestation	
diff --git a/test_suite/refresh_golden.sh b/test_suite/refresh_golden.sh
@@ -24,7 +24,7 @@ for FILE in "$@" ; do
         echo "Could not read: \"$FILE\"" 2>&1
         exit 1
     fi
-    jsonnet "$FILE" > "${FILE}.golden" 2>&1
+    ../jsonnet "$FILE" > "${FILE}.golden" 2>&1
 done