Parse leading negatives (#896)

src/main/java/com/hubspot/jinjava/tree/parse/ExpressionToken.java

@@ -44,16 +44,7 @@ public int getType() {
   @Override
   protected void parse() {
     this.expr = WhitespaceUtils.unwrap(image, "{{", "}}");
-
-    if (WhitespaceUtils.startsWith(expr, "-")) {
-      setLeftTrim(true);
-      this.expr = WhitespaceUtils.unwrap(expr, "-", "");
-    }
-    if (WhitespaceUtils.endsWith(expr, "-")) {
-      setRightTrim(true);
-      this.expr = WhitespaceUtils.unwrap(expr, "", "-");
-    }
-
+    this.expr = handleTrim(expr);
     this.expr = StringUtils.trimToEmpty(this.expr);
   }
 

src/main/java/com/hubspot/jinjava/tree/parse/TagToken.java

@@ -16,7 +16,6 @@
 package com.hubspot.jinjava.tree.parse;
 
 import com.hubspot.jinjava.interpret.TemplateSyntaxException;
-import com.hubspot.jinjava.util.WhitespaceUtils;
 
 public class TagToken extends Token {
   private static final long serialVersionUID = -4927751270481832992L;
@@ -54,15 +53,7 @@ protected void parse() {
     }
 
     content = image.substring(2, image.length() - 2);
-
-    if (WhitespaceUtils.startsWith(content, "-")) {
-      setLeftTrim(true);
-      content = WhitespaceUtils.unwrap(content, "-", "");
-    }
-    if (WhitespaceUtils.endsWith(content, "-")) {
-      setRightTrim(true);
-      content = WhitespaceUtils.unwrap(content, "", "-");
-    }
+    content = handleTrim(content);
 
     int nameStart = -1, pos = 0, len = content.length();
 

src/main/java/com/hubspot/jinjava/tree/parse/Token.java

@@ -83,6 +83,25 @@ public void setRightTrimAfterEnd(boolean rightTrimAfterEnd) {
     this.rightTrimAfterEnd = rightTrimAfterEnd;
   }
 
+  /**
+   * Handle any whitespace control characters, capturing whether leading or trailing
+   * whitespace should be stripped.
+   * @param unwrapped the content of the block stripped of its delimeters
+   * @return the content stripped of any whitespace control characters.
+   */
+  protected final String handleTrim(String unwrapped) {
+    String result = unwrapped;
+    if (unwrapped.startsWith("-")) {
+      setLeftTrim(true);
+      result = unwrapped.substring(1);
+    }
+    if (unwrapped.endsWith("-")) {
+      setRightTrim(true);
+      result = unwrapped.substring(0, unwrapped.length() - 1);
+    }
+    return result;
+  }
+
   public int getStartPosition() {
     return startPosition;
   }

src/test/java/com/hubspot/jinjava/interpret/JinjavaInterpreterTest.java

@@ -335,7 +335,7 @@ public void itHidesWarningErrors() {
 
   @Test
   public void itBindsUnaryMinusTighterThanCmp() {
-    assertThat(interpreter.render("{{ (-5 > 4) }}")).isEqualTo("false");
+    assertThat(interpreter.render("{{ -5 > 4 }}")).isEqualTo("false");
   }
 
   @Test
@@ -351,17 +351,34 @@ public void itBindsUnaryMinusTighterThanIsNot() {
 
   @Test
   public void itBindsUnaryMinusTighterThanFilters() {
-    assertThat(interpreter.render("{{ (-5 | abs) }}")).isEqualTo("5");
+    assertThat(interpreter.render("{{ -5 | abs }}")).isEqualTo("5");
+  }
+
+  @Test
+  public void itBindsUnaryMinusTighterThanPlus() {
+    assertThat(interpreter.render("{{ -10 + 4 }}")).isEqualTo("-6");
+    assertThat(interpreter.render("{{ 4 + -10 }}")).isEqualTo("-6");
   }
 
   @Test
   public void itBindsFiltersTighterThanMul() {
-    assertThat(interpreter.render("{{ (-5 * -4 | abs) }}")).isEqualTo("-20");
+    assertThat(interpreter.render("{{ -5 * -4 | abs }}")).isEqualTo("-20");
+  }
+
+  @Test
+  public void itBindsFiltersTighterThanPlus() {
+    assertThat(interpreter.render("{{ -10 | abs + 4 }}")).isEqualTo("14");
+    assertThat(interpreter.render("{{ 4 + -10 | abs }}")).isEqualTo("14");
   }
 
   @Test
   public void itInterpretsFilterChainsInOrder() {
     assertThat(interpreter.render("{{ 'foo' | upper | replace('O', 'A') }}"))
       .isEqualTo("FAA");
   }
+
+  @Test
+  public void itInterpretsStandaloneNegatives() {
+    assertThat(interpreter.render("{{ -10 }}")).isEqualTo("-10");
+  }
 }

src/test/resources/eager/handles-deferred-in-ifchanged.jinja

@@ -1,6 +1,6 @@
 {% set foo = [1, 1, 2, 1] %}
 {%- for item in foo -%}
-{%- ifchanged item- %}
+{%- ifchanged item -%}
 {{ deferred[item] }}
 {%- endifchanged -%}
 {% endfor%}