Release v1.11.5

- Add a built-in function. ([Github #10](#10))
  - String Function
      - SUBSTRING

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Change Log
 
+## Version 1.11.5
+
+Released on July 6, 2019
+
+- Add a built-in function. ([Github #10](https://github.com/mithrandie/csvq/pull/10))
+  - String Function
+    - SUBSTRING
+
 ## Version 1.11.4
 
 Released on Jun 1, 2019

docs/_posts/2006-01-02-string-functions.md

@@ -22,7 +22,8 @@ category: reference
 | [WIDTH](#width) | Return the string width of a string |
 | [LPAD](#lpad) | Return a string left-side padded |
 | [RPAD](#rpad) | Return a string right-side padded |
-| [SUBSTR](#substr) | Return the substring of a string |
+| [SUBSTRING](#substring) | Return the substring of a string |
+| [SUBSTR](#substr) | Return the substring of a string using zero-based indexing |
 | [INSTR](#instr) | Return the index of the first occurrence of a substring |
 | [LIST_ELEM](#list_elem) | Return a element of a list |
 | [REPLACE](#replace) | Return a string replaced the substrings with another string |
@@ -327,11 +328,13 @@ _return_
 
 Returns the string value of _str_ padded with trailing _padstr_ to a length specified by _len_.
 
-### SUBSTR
-{: #substr}
+
+### SUBSTRING
+{: #substring}
 
 ```
-SUBSTR(str, position)
+SUBSTRING(str FROM position [FOR len])
+SUBSTRING(str, position [, len])
 ```
 
 _str_
@@ -340,14 +343,24 @@ _str_
 _position_
 : [integer]({{ '/reference/value.html#integer' | relative_url }})
 
+_len_
+: [integer]({{ '/reference/value.html#integer' | relative_url }})
+
 _return_
 : [string]({{ '/reference/value.html#string' | relative_url }})
 
-Returns the substring of _str_ from at _position_ to the end.
+Returns the _len_ characters in _str_ starting from the _position_-th character using one-based positional indexing.
+
+If _position_ is 0, then it is treated as 1.<br />
+if _len_ is not specified or _len_ is longer than the length from _position_ to the end, then returns the substring from _position_ to the end.<br /> 
 If _position_ is negative, then starting position is _position_ from the end of the _str_.
 
+
+### SUBSTR
+{: #substr}
+
 ```
-SUBSTR(str, position, len)
+SUBSTR(str, position [, len])
 ```
 
 _str_
@@ -362,8 +375,8 @@ _len_
 _return_
 : [string]({{ '/reference/value.html#string' | relative_url }})
 
-Returns the _len_ characters in _str_ from at _position_.
-if _len_ is less than the length from _position_ to the end, then returns the substring from _position_ to the end. 
+This function behaves the same as [SUBSTRING](#substring), but uses zero-based positional indexing.
+
 
 ### INSTR
 {: #instr}

docs/changelog.md

@@ -5,6 +5,14 @@ title: Change Log - csvq
 
 # Change Log
 
+## Version 1.11.5
+
+Released on July 6, 2019
+
+- Add a built-in function. ([Github #10](https://github.com/mithrandie/csvq/pull/10))
+  - String Function
+    - SUBSTRING
+
 ## Version 1.11.4
 
 Released on Jun 1, 2019

docs/index.md

@@ -13,10 +13,10 @@ In the multiple operations, you can use variables, cursors, temporary tables, an
 
 ## Latest Release
 
-Version 1.11.4
-: Released on Jun 1, 2019
+Version 1.11.5
+: Released on July 6, 2019
 
-  <a class="waves-effect waves-light btn" href="https://github.com/mithrandie/csvq/releases/tag/v1.11.4">
+  <a class="waves-effect waves-light btn" href="https://github.com/mithrandie/csvq/releases/tag/v1.11.5">
     <i class="material-icons left">file_download</i>download
   </a>
 

docs/sitemap.xml

@@ -6,7 +6,7 @@
             http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
     <url>
         <loc>https://mithrandie.github.io/csvq/</loc>
-        <lastmod>2019-06-01T12:10:32+00:00</lastmod>
+        <lastmod>2019-07-06T02:12:43+00:00</lastmod>
     </url>
     <url>
         <loc>https://mithrandie.github.io/csvq/reference.html</loc>
@@ -150,7 +150,7 @@
     </url>
     <url>
         <loc>https://mithrandie.github.io/csvq/reference/string-functions.html</loc>
-        <lastmod>2019-04-25T16:32:19+00:00</lastmod>
+        <lastmod>2019-07-06T02:12:43+00:00</lastmod>
     </url>
     <url>
         <loc>https://mithrandie.github.io/csvq/reference/numeric-functions.html</loc>

lib/parser/ast.go

@@ -762,10 +762,23 @@ type Function struct {
 	*BaseExpr
 	Name string
 	Args []QueryExpression
+	From string
+	For  string
 }
 
 func (e Function) String() string {
-	return e.Name + "(" + listQueryExpressions(e.Args) + ")"
+	var args string
+	if strings.EqualFold(e.Name, TokenLiteral(SUBSTRING)) && 0 < len(e.From) {
+		elems := make([]string, 0, 5)
+		elems = append(elems, e.Args[0].String(), e.From, e.Args[1].String())
+		if 0 < len(e.For) {
+			elems = append(elems, e.For, e.Args[2].String())
+		}
+		args = joinWithSpace(elems)
+	} else {
+		args = listQueryExpressions(e.Args)
+	}
+	return e.Name + "(" + args + ")"
 }
 
 type AggregateFunction struct {

lib/parser/ast_test.go

@@ -1024,6 +1024,47 @@ func TestFunction_String(t *testing.T) {
 	if e.String() != expect {
 		t.Errorf("string = %q, want %q for %#v", e.String(), expect, e)
 	}
+
+	e = Function{
+		Name: "substring",
+		Args: []QueryExpression{
+			Identifier{Literal: "column"},
+			NewIntegerValue(2),
+			NewIntegerValue(5),
+		},
+	}
+	expect = "substring(column, 2, 5)"
+	if e.String() != expect {
+		t.Errorf("string = %q, want %q for %#v", e.String(), expect, e)
+	}
+
+	e = Function{
+		Name: "substring",
+		Args: []QueryExpression{
+			Identifier{Literal: "column"},
+			NewIntegerValue(2),
+		},
+		From: "from",
+	}
+	expect = "substring(column from 2)"
+	if e.String() != expect {
+		t.Errorf("string = %q, want %q for %#v", e.String(), expect, e)
+	}
+
+	e = Function{
+		Name: "substring",
+		Args: []QueryExpression{
+			Identifier{Literal: "column"},
+			NewIntegerValue(2),
+			NewIntegerValue(5),
+		},
+		From: "from",
+		For:  "for",
+	}
+	expect = "substring(column from 2 for 5)"
+	if e.String() != expect {
+		t.Errorf("string = %q, want %q for %#v", e.String(), expect, e)
+	}
 }
 
 func TestAggregateFunction_String(t *testing.T) {