Loop Structures

Quantum provides powerful loop structures inspired by ColdFusion's cfloop but designed for modern declarative programming. All loops support variable databinding and can be nested.

Loop Types

Quantum supports three main loop types:

Range Loop (type="range")

Iterates over a numeric range with optional step.

<q:component name="RangeExample" xmlns:q="https://quantum.lang/ns">
  <q:loop type="range" var="i" from="1" to="5">
    <q:return value="Number {i}" />
  </q:loop>
</q:component>

Output: ["Number 1", "Number 2", "Number 3", "Number 4", "Number 5"]

With Step

<q:loop type="range" var="i" from="1" to="10" step="2">
  <q:return value="Odd: {i}" />
</q:loop>

Output: ["Odd: 1", "Odd: 3", "Odd: 5", "Odd: 7", "Odd: 9"]

Array Loop (type="array")

Iterates over JSON arrays with optional index tracking.

<q:component name="ArrayExample" xmlns:q="https://quantum.lang/ns">
  <q:loop type="array" var="fruit" items='["apple", "banana", "orange"]'>
    <q:return value="Fruit: {fruit}" />
  </q:loop>
</q:component>

Output: ["Fruit: apple", "Fruit: banana", "Fruit: orange"]

With Index

<q:loop type="array" var="fruit" index="idx" items='["apple", "banana", "orange"]'>
  <q:return value="{idx}: {fruit}" />
</q:loop>

Output: ["0: apple", "1: banana", "2: orange"]

List Loop (type="list")

Iterates over delimited strings.

<q:component name="ListExample" xmlns:q="https://quantum.lang/ns">
  <q:loop type="list" var="color" items="red,green,blue">
    <q:return value="Color: {color}" />
  </q:loop>
</q:component>

Output: ["Color: red", "Color: green", "Color: blue"]

Custom Delimiter

<q:loop type="list" var="name" items="João|Maria|Pedro" delimiter="|">
  <q:return value="Name: {name}" />
</q:loop>

Output: ["Name: João", "Name: Maria", "Name: Pedro"]

Advanced Features

Arithmetic in Databinding

All loops support arithmetic expressions in variable databinding:

<q:loop type="range" var="i" from="1" to="3">
  <q:return value="Item {i}, Next: {i + 1}, Double: {i * 2}" />
</q:loop>

Output: ["Item 1, Next: 2, Double: 2", "Item 2, Next: 3, Double: 4", "Item 3, Next: 4, Double: 6"]

Nested Loops

Loops can be nested for complex data processing:

<q:component name="NestedExample" xmlns:q="https://quantum.lang/ns">
  <q:loop type="range" var="x" from="1" to="2">
    <q:loop type="range" var="y" from="1" to="2">
      <q:return value="({x},{y})" />
    </q:loop>
  </q:loop>
</q:component>

Output: ["(1,1)", "(1,2)", "(2,1)", "(2,2)"]

Integration with Conditionals

Loops work seamlessly with conditional logic:

<q:loop type="range" var="i" from="1" to="5">
  <q:if condition="i % 2 == 0">
    <q:return value="{i} is even" />
  <q:else>
    <q:return value="{i} is odd" />
  </q:else>
  </q:if>
</q:loop>

Syntax Reference

Range Loop Attributes

• type="range" - Loop type identifier
• var="varname" - Variable name for current iteration value
• from="start" - Starting number (inclusive)
• to="end" - Ending number (inclusive)
• step="increment" - Step size (optional, default: 1)

Array Loop Attributes

• type="array" - Loop type identifier
• var="varname" - Variable name for current array item
• items="[...]" - JSON array or variable reference
• index="indexvar" - Variable name for current index (optional)

List Loop Attributes

• type="list" - Loop type identifier
• var="varname" - Variable name for current list item
• items="item1,item2,..." - Delimited string or variable reference
• delimiter="," - Delimiter character (optional, default: comma)
• index="indexvar" - Variable name for current index (optional)

Error Handling

Quantum provides helpful error messages for common loop issues:

• Missing variable name: Loop requires 'var' attribute
• Invalid range: Range loop requires 'from' and 'to' attributes
• Invalid JSON: Falls back to string parsing for arrays
• Empty collections: Loops with empty data simply don't execute

Performance Notes

• Range loops are most efficient for numeric iterations
• Array loops support large datasets well
• List loops automatically trim whitespace from items
• Nested loops should be used judiciously for large datasets

Coming Soon

Future loop enhancements planned:

• Object/Structure loops (type="object")
• Query/Database loops (type="query")
• Conditional loops (type="while")
• Parallel execution options